dzx.cz

December

matousdzivjak@gmail.com (Matouš Dzivjak) — Thu, 01 Jan 2026 00:00:00 +0000

Reading

Top of the Charts: our most popular work in 2025

Watching

Russians at War - Inside a Russian Battalion on the Front Lines in Ukraine (Full Documentary) by Anastasia Trofimova

Agentic ProbLLMs: Exploiting AI Computer-Use and Coding Agents

Who cares about the Baltic Jammer?

All my Deutschlandtickets gone: Fraud at an industrial scale

Bluetooth Headphone Jacking: A Key to Your Phone

To sign or not to sign: Practical vulnerabilities in GPG & friends

November

matousdzivjak@gmail.com (Matouš Dzivjak) — Mon, 01 Dec 2025 00:00:00 +0000

Long Dark Tea-Time of the Soul

matousdzivjak@gmail.com (Matouš Dzivjak) — Thu, 13 Nov 2025 00:00:00 +0000

I bought Long Dark Tea-Time of the Soul in Bucharest while visiting for a wedding. I loved Adams’s The Hitchhiker’s Guide to the Galaxy, and I enjoy Long Dark Tea-Time of the Soul too.

Adam’s writing style is hard to describe, but he’s able to build otherwise mundane sentences in a style that makes me chuckle and appreciate the craft of writing. Long Dark Tea-Time of the Soul is a fun read, not as funny as The Hitchhiker’s Guide to the Galaxy series, nor as thrilling as other novels I read over the last years, but it’s fun nevertheless. This book is a good buy and finish on vacation buy for lightweight reading.

October

matousdzivjak@gmail.com (Matouš Dzivjak) — Sat, 01 Nov 2025 00:00:00 +0000

September

matousdzivjak@gmail.com (Matouš Dzivjak) — Wed, 01 Oct 2025 00:00:00 +0000

Reading about rogue waves reminded me of The Clock Is Ticking, a long-form investigative article by William Langewiesche who I learned died this year on June 15 at age 70. William’s writing

The Electric Typewriter

This Month I Learned

Toyota Comfort

Reading

A chronology of freaque wave encounters (pdf) about rogue waves that likely sank MS München, the Ocean Ranger, and more.

Listening

Evicted

matousdzivjak@gmail.com (Matouš Dzivjak) — Sun, 28 Sep 2025 00:00:00 +0000

I got Evicted after going through Tom MacWright’s top rated books, not knowing what to expected.

Desmod’s Evicted is a collection of stories of people living on the edge of poverty focusing on the threat of evictions. Desmod closely follows stories of people living in Milwaukee, throughout their struggle to keep a roof over theirs, and theirs children, head. It illustrates many things that are wrong about the socialism in USA, from ill-setup support programs to a system that makes it neigh impossible for people to get back on their feet.

Evicted ends with a few suggestions for a better system for people and the government, for both of whom the existing system is expensive, inefficient, and outright broken. The only beneficiaries of status quo are landlords, often robbing the country of its money, and people of their prospects of a stable life.

Pathogenesis

matousdzivjak@gmail.com (Matouš Dzivjak) — Tue, 23 Sep 2025 00:00:00 +0000

August

matousdzivjak@gmail.com (Matouš Dzivjak) — Mon, 01 Sep 2025 00:00:00 +0000

Badlands

Reading

Watching

Andrew Reece – Assuming as Much as Possible – BSC 2025

Listening

July

matousdzivjak@gmail.com (Matouš Dzivjak) — Fri, 01 Aug 2025 00:00:00 +0000

A belated update for July from onboard a flight to Japan.

July has been a work-intensive month with a quick break in the middle. We met with the team in Koln for a 4 day long off-site and socializing which has been fun and productive but not nearly enough for us to cover all the topics we needed. I left on Thursday afternoon and on an early Saturday morning we were already on a flight to Italy to meet with my parents in a Tuscany for a week of sun, relax, and good food.

Reading

Listening

June

matousdzivjak@gmail.com (Matouš Dzivjak) — Tue, 01 Jul 2025 00:00:00 +0000

In June I ran Mozart Ultra in Salzburg, Austria. It has a friendly elevation profile similar to Istria with the hard climbs cramped in the first half and second half being more flat. Even with these parameters, forgetting running sticks at home was a huge mistake and my quads were hurting from 70km onwards. Furthermore, I didn’t eat nearly enough which turned out alright, but might have killed my race if it was any longer. In the end, 35th place (out of 411) and valuable experience for next time (Kullamannen in Sweden in the autumn).

Week later we flew to Israel to visit Iris’s family (and there’s a lot of it). Iris’s dad picked us up at the airport and a few minutes later we were joined by her niece - Amit - a 1 meter 50 petite girl that came in an army uniform with a gun her size hanging from her shoulder. We came for me to meet everyone, eat, and visit a few places…

As it turned out, we also arrived just in time for Israel to bomb Iran and kick-off a nightly missile exchange that bound us to the vicinity of a makbuba at Maya’s (Iris’s sister) place for the foreseeable future. A short 5 day visit quickly turned into a 2 weeks long sleepless vacation with every single night interrupted with sirens to warn against incoming missiles.

After a couple of days of suspended commercial flights and no de-escalation in sight we started looking for a way out. For me this meant checking with the Czech embassy whether there will be another repatriation flight and for Iris the same, except with the Germans. I got lucky, Iris didn’t. The Czech embassy was planning another flight from Egypt and I got on the list for it. On the other hand, German website for the registration of people traveling abroad didn’t accept any other identification number than German ID, excluding all residents without a citizenship out of the repatriation process.

In the end, I headed home on the 25th - 10 days later than planned - onboard the Czech Special, a state-owned Airbus A319CJ, flying from the private terminal of Sharm El Sheikh airport (SSH) and landing in the Kbely (LKKB) army airport in Prague. Iris arrived 2 days later, taking the first outbound flight from Tel Aviv to Rome, staying there over night, and then flying to Berlin with another airline.

It’s been a full Israeli experience, great food, hot weather, and missiles overhead.

Reading

Listening

1Password - Andrew Burkhart, Senior Rust Engineer

The Code Book

matousdzivjak@gmail.com (Matouš Dzivjak) — Wed, 11 Jun 2025 00:00:00 +0000

The Code Book is a short and approachable introduction to cryptography. On 200 pages it goes through Caesar and Vigenere cipher through enigma all the way to Diffie-Hellman key exchange and RSA public key cryptography. It’s a good book if these topics are new to you, but even with basic knowledge of cryptography and mathematics it falls short and the stories from the history on their own don’t make it worthwhile read. For a summary of this book, see:

Or go more in-depth with the details of the Signal protocol:

Seven Serpents 2025

matousdzivjak@gmail.com (Matouš Dzivjak) — Tue, 27 May 2025 00:00:00 +0000

Seven Serpents is an unsupported bikepacking gravel race from Ljubljana, Slovenia to Trieste, Italy. The 2025 route was 840 km long with over 17,000 m elevation gain which I finished in 3 days 4 hours and 44 minutes. It was challenging, technical, and unnecessarily hard - from hike-a-bike sections to downhills with coconut-size rocks that required a lot of attention, constantly pressing on breaks, and a snail tempo to avoid punctures or falls. A proper type 2 fun.

The race started on Sunday, 7 am at Ljubljana. We had a clear sky and 8 degrees, which wouldn’t last long. The race split immediately on the first climb that had sections with 20% gradient and wouldn’t come back together until the social dinner on Thursday after the race (many riders were still riding by then). The first part winded through hills and nice gravel routes, taking us slowly from Ljubljana to Cerknice at 200th kilometer with the first checkpoint on the way at Sveta Trojica Hill at 1123 meters of altitude.

The weather turned to shit not long after the race start and wouldn’t improve until the Monday morning almost a day later. In between heavy rain we go swept by thunderstorms and hail. I have spent first few hours riding with Zuzka, later joined by Ben, until I punctured on 140th kilometer and lost 20 minutes trying to plug a hole in my tubeless tires that wouldn’t to seal.

After passing Sveta Trojica I tried to ride at a solid tempo to catch up with Zuzka and Ben again and have a companionship for the night. I failed, meeting them for a few minutes at Cerknica where I wanted to resupply and eat. I made my first mistake here trying to rush through to gain back time. I had only a few bites of a kebab as my stomach didn’t feel like having more, I accidentally got Coca Cola Zero instead of regular, and I didn’t cool down at all. Zuzka and Ben were long gone, and I left into the sunset on my own, accompanied only by a steady heavy rain.

By 21:30 I was drenched, cold, and uncontrollably shivering and decided to stop at a hut for a cup of tea to reassess the situation. Reassessing the situation took 5 minutes and one more cup of tea - I decided to stay for the night and leave in the early morning hours, hopefully into a better weather and warmer temperatures.

Second day started at 4:30 am with a long route ahead. First, 64 kilometers to checkpoint number 2 at the Guslica mountain, all of which was in a rain and mist that reduced the visibility to 200 meters. Climb to Guslica was horrendous with big rocks and heavy wind gusts, furthermore, we rode the same road down. It had a silver lining too, after descending further to the south the weather improved, sun came out, and I had a first proper stop at a bakery where I chugged on a yogurt, 2 berliners, and 2 sausage rolls. With a better mood and restored energy I pressed on towards the Krk island.

The part of the race on the Krk island start on 370th kilometer. By that time it was afternoon and warm and sunny, but the steep climbs ensured one doesn’t get too comfortable. The gnarliest section was around Baška at the south-east of the island. A technical descend on a hiking trail followed by a hike-a-bike climb on the other side of the town. The rest of the route on the Krk island was still challenging but passed by faster with the first ferry in sight.

The crux of Seven Serpents are two ferries, one from the Krk island to Cres and another one from Cres back to the Croatian mainland. While the ferry from Krk to Cres goes in regular intervals late into the night, the ferry the decides the race is the one from Cres to mainland. The last evening ferry runs at 9pm and next one only at 6am the next day. During the 2024 edition only one person made it for the afternoon departure and not surprisingly won the race. To reach this ferry in time, one would have to maintain average speed of 16.3 km/h for the first 560 km of the race. Not an unachievable feat on a gravel bike, but a heroic feat on the technical route of Seven Serpents.

I have reached the first ferry at 19:11 with 4 minutes left until departure. Quick stop at a gas station for food and drinks saved me a fortune as the ferry buffet was overpriced and under supplied. On the ferry I reunited with Ben who had a rough day with a few falls. The short - 20 minute sail - meant enough time to eat, drink, and dress up for the night but no rest. The goal was to continue into late night that day and sleep in Beli, village another 50 kilometers further on Cres. Disembarking the ferry I turned off my brain, turned on music in my headphones, and phased out until reaching the accommodation at midnight.

The top riders all met at the 6am ferry, I slept in and was the only one to take the next one at 9am, having a long road ahead. From the ferry, we climbed all the way to the top of the Vojak hill at 1364 m which took better part of the morning all the way into the afternoon. After Vojak I had a rough time and was low on energy, scouting for first chance to stop and eat which didn’t come for another 50 km until reaching Buzet. Excited about a seeing a grocery store I turned sharply and fell on a wet road, injuring my wrist, palm, tight, and elbow. Licking my wounds I bought a lot of food and decided to ride further to see if the pain will numb or not.

Ride from Buzet was tough, I wasn’t having a good time. Luckily, I met Yuri - a Belgian rider - an hour later and a little chit chat brought me back up. With the regained energy and optimism I set my sight on Novigrad on 720th kilometer as the next stop and kept pedaling. In the meantime I called Iris to chat, and ask her to book me an accommodation for the night to give the body a little rest before the final push to the finish line. At 21:00 I arrived to Brtonigla where I stayed for the night.

Waking up early was easy with only 110 km left to go. I quickly checked our WhatsApp group to learn that Ondra, a friend, finished in 3rd place in the night and Zuzka arrived not long after, securing the first woman spot and 4th place overall. On the first climb of the last day I met Leonard from Switzerland with whom I talked a rode with for next 2 hours before leaving him behind, and focusing on the last big climb of the race. The last peak was Slavnik at 1028 meter. It was raining again but withg 2 hours left I couldn’t care less anymore; onward towards the finish line.

I reached Trieste 12:01 after 3 days, 4 hours, and 44 minutes with overall average speed (including stops) of 10.94 km/h. My whole body was sore, but I was happy - first gravel race done and dusted and compared to trail running - no stomach issues for the whole race. As I am writing this report, I have 10 days left until the Mozart Ultra race in Salzburg, my legs are still tired, but I think I learned my lesson in slow and steady wins the race. Until the next time, bye.

Bike

Basso Palta (2023 model) in a stock configuration with shorter stem (90mm).

Group set: Sram Rival 1X12 ETAP AXS
Chain ring: Wolf Tooth 130 BCD Gravel, 38T
Tires: Tufo Gravel Thundero HD, prototypes, provided by Tufo for testing for the race
Wheels: Zipp 303s
Bags: Apidura Racing Bolt-On Top Tube Pack, Apidura Expedition Frame Pack, and Apidura Expedition Saddle Pack
Lights: Fenix BC26R Rechargeable Bike Light and Fenix BC05R V2.0 Rechargeable Bike Taillight
Bike computer: Coros Dura
Extras: Uswe Rush 8L Bike Hydration Vest

Numbers Don't Lie

matousdzivjak@gmail.com (Matouš Dzivjak) — Fri, 09 May 2025 00:00:00 +0000

From child mortality rates as a nation development indicator to the impossibility of net-zero by 2025 Numbers Don’t Lie summarizes many facts and numbers that drive our world in 71 short chapters. It’s similar in content to Vaclav’s How the World Really Works, just quicker and more approachable.

April

matousdzivjak@gmail.com (Matouš Dzivjak) — Thu, 01 May 2025 00:00:00 +0000

I have been catching up with all the recent development in the world of LLMs and Agentic Workflows. Deepseek made a splash beginning of the year but apart from bigger models the only recent interesting development is the sky-rocketing adoptions of MCP about which I wrote more in SumUp MCP atom.

Reading

What If We Made Advertising Illegal

Modern Day Oracles or Bullshit Machines? is a collection of lessons for the world of ChatGPT where anything can be bullshit. It’s an exceptionally well-done multi-chapter curriculum suitable for class rooms.

One afternoon around 4:50 p.m. John von Neumann came by and saw what Fermi had on the blackboard and asked what he was doing. So Enrico told him and John von Neumann said “That’s very interesting.” He came back about 15 minutes later and gave him the answer. Fermi leaned against his doorpost and told me, “You know that man makes me feel I know no mathematics at all.”

Working With Fermi at Chicago and Post-war Los Alamos by Richard L. Garwin hints at the greatness of John von Neumann. It was cited in a random Reddit thread alongside other quotes, stories, and achievements of which I was embarrassingly mostly familiar with von Neumann architecture and his contributions to the computer science. As it turns out, von Neumann’s contributions span mathematics, physics, economics, and statistics in just as much depth in what amounts to a career with field-coverage and significance unmatched during his life.

Your Life in Weeks

The core narrative control is straightforward: 1) everything’s great, and 2) if it’s not great, it’s going to be great. Whatever’s broken is going to get fixed, AI is wunnerful, and so on.

I Quit! The Tsunami of Burnout Few See hits close to home. Every company all-hands with talk about EBITDA, active users, product adoption but when the time comes for the tough discussion regarding last eNPS survey, we get a few empty promises and then hear about the declining score until the next survey. I came to terms with the company being purely for-profit (albeit nobody is able to state it clearly) and I know that assuming anything else was foolish. Yet, I still naively hope that one day, we put people first.

Watching

About the magic behind the speed and responsiveness of Linear. Linear uses mobx for state management and relies heavily on offline-first approach for responsiveness.

This month I learned

Hilber curve

The Hilbert curve is a continuous fractal space-filling curve first described by the German mathematician David Hilbert in 1891, as a variant of the space-filling Peano curves discovered by Giuseppe Peano in 1890.

March

matousdzivjak@gmail.com (Matouš Dzivjak) — Tue, 01 Apr 2025 00:00:00 +0000

Reading

Accountability sinks hits close to home and I think I will be ordering Dan Davie’s The Unaccountability Machine.

Other fun reads discovered through RSS subscriptions and Hacker News:

The carefulness knob
The Night Watch by James Mickens

This Month I Learned

Gall’s law:

A complex system that works is invariably found to have evolved from a simple system that worked. A complex system designed from scratch never works and cannot be patched up to make it work. You have to start over with a working simple system. John Gall (1975) Systemantics: How Systems Really Work and How They Fail

Watching

I will be ticking off one huge item on my bucket list this summer by racing Badlands, a 800km +16.000m gravel race in Granada / Almería - Spain. No better way to get motivated for long training rides than by watching Lachlan Morton’s record ride around Australia.

Another race I kept an eye on - the most grueling, brutal, and impossible race - is the Barkley Marathons conceived by Gary “Lazarus Lake” Cantrell (the man that’s also behind Big’s Backyard Ultra) and held at Frozen Head State Park in Tennessee. This year, nobody finished, but documentary of Jasmin Paris’s finish last year (first woman to finish the race) is a worthwhile watch providing insight into just how tough and demanding the race is.

February

matousdzivjak@gmail.com (Matouš Dzivjak) — Sat, 01 Mar 2025 00:00:00 +0000

Reading

I Tasted Honda’s Spicy Rodent-Repelling Tape, and no, the title is not a metaphor, it’s literally an article about licking Honda’s Spicy Rodent-Repelling tape and is just as much fun as it sounds like.

Ava’s the ‘return to office’ lies resonates well with my opinions on the return to office policy. Fake positivism, more work, more responsibility, but hey - come to the office, socialize, waste your time on commutes, we know the best.

Obscure Islands I Find Interesting

Listening

On Writing: A Memoir of the Craft

matousdzivjak@gmail.com (Matouš Dzivjak) — Fri, 28 Feb 2025 00:00:00 +0000

I find it hard to write about books I read. Damn, I find it hard to write about other things too. My best output to this date are technical work-related documents. What I can say for certainty though, is that Stephen King’s writing is a delight.

On Writing is a memoir, guide for aspiring writers, and a showcase of what mastering the craft means. It starts with snippets of Stephen’s life, from childhood to adolescence. From wiping his ass with poison ivy, to facing his alcohol and drug addiction. And all of it is fun, honest, and not nearly as long as I would love it to be.

If Stephen’s life is a starter, writing itself it the main course; and Stephen is brutally honest about who will be eating. There are good writers, and those can get better. There are great writers, and those can get exceptional. But not everyone is born a writer, and bad writers will, in large, stay bad writers.

Stephen says to “Write with the door closed, rewrite with the door open”. First, write for yourself, and an imaginary IR (Ideal Reader) - be that your wife, friend, or deceased relative. Once you get your story right and out there, it belongs to any who wants to read it.

Take a noun, put it with a verb, and you have a sentence. Write with active voice, avoid adverbs (especially in dialog attributions), and stick with the first word that comes to you mind if it’s appropriate and colorful. If you do the basics right, and got a story to tell, you are on the right path. For all the other rules, there’s The Elements of Style.

“Every book you pick up has its own lesson”; On Writing is lesson in witty writing, story telling, and fulfilled life. A worthwhile read.

Notes

Writing it telepathy. The writer has an image in their mind, and if they do good enough job, their image is translated through paper and time into the readers mind.
Cardinal rule of fiction - Show, don’t tell.
Good fiction begins with a story and progresses to a theme. I like to imagine that Neal Stephenson begun his Seveneves) by jotting The moon blew up without warning and for no apparent reason_ on a napkin and ended up with a novel a year later.
You learn the best, as with any other craft, by writing a lot and reading a lot.
Best form of dialog attribution is “he/she/they said”.
Best writing comes from observing how real people behave, and then telling the truth about what you see.

In my view, stories and novels consist of three parts: narration, which moves the story from point A to point B and finally to point Z; description, which creates a sensory reality for the reader; and dialogue, which brings characters to life through their speech.

Hard landing

matousdzivjak@gmail.com (Matouš Dzivjak) — Sun, 23 Feb 2025 00:00:00 +0000

The Selfish Gene

matousdzivjak@gmail.com (Matouš Dzivjak) — Sun, 23 Feb 2025 00:00:00 +0000

Why We're Polarized

matousdzivjak@gmail.com (Matouš Dzivjak) — Sun, 23 Feb 2025 00:00:00 +0000

Ezra Klein’s Why We’re Polarized is now as relevant and timely as it gets. In outlines the shift in the U.S. politics over the course of 20th century all the way to present day, with the most important takeaway being that current status isn’t a fluke, but the natural result of a self-feeding polarization loop and the psychological and structural forces at hand.

Modern politics revolve around identities. Over the last 50 years our partisan identities merge with the racial, religious, cultural, and geographical. These identities serve as triggers for a greater divide to the point where the loss of the other party becomes the most important factor. In that way, politics has become a fan sport, where the more invested a person is, the more likely they are to ignore reason and facts in favor of their own agenda.

There is much more to Why We’re Polarized, it’s an insightful read that makes one aware of the subtle psychological tendencies that news outlets learned to play so well.

January

matousdzivjak@gmail.com (Matouš Dzivjak) — Sat, 01 Feb 2025 00:00:00 +0000

Not much for January, a calm month, no travels, no side projects - an off-season for work. I will be back to posting when I feel like and have something to share, until then 👋

Reading

William Strunk Jr.’s The Elements of Style is a quick read. The is century old at this point, but stands the test of time. Internet suggests it’s inaccurate in parts, and outdated in others, but if nothing else - it’s a good reminder of the very basics of writing well.

Watching

Watch: Inside the FBI’s Secret Phone Company by Joseph Cox from the 404 media. The talk is available on YouTube:

The Elements of Style

matousdzivjak@gmail.com (Matouš Dzivjak) — Sat, 18 Jan 2025 00:00:00 +0000

The Elements of Style, a century old at this point, is a handy reference of basic literary and grammar principles for writers. It’s references as the main inspiration for William Zinsser’s On Writing Well and the most popular text assigned in syllabuses.

One the internet, the opinions vary, between a the book being a must-read and it being outdated and containing inaccurate grammar advices. Nevertheless, it’s a short read, and even if inaccurate it server well as a reminder of writing principles of the uttermost importance.

Notes

The Elements of Style is better kept at hand as a readers manual. Thus, the notes here are brief and reduced to what I found important in particular. Core principle, obvious but often neglected, is: be clear, concise, put your self in the background, and rely on basic construct unless you are certain of what you are doing.

Elementary rules

Use serial commas

also referred to as the series comma, Oxford comma, or Harvard comma
Place a comma before a conjunction introducing an independent clause
Join independent clauses grammatically completing each other with a semicolon
Use a dash to set off an abrupt break or interruption and to announce a long appositive or summary

Composition

Paragraph is the unit of composition. Paragraph may be of any length as long as it holds together.
Use active voice, unless making a particular word of a sentence the subject calls for a passive voice.
Put statements in a positive form (“He was not keen of flavored coffee” should be replaced by “He disliked flavored coffee”).
Use definitive, specific, concrete language
Omit needles words
Keep related words together
The place for the most prominent a word or group of words is usually at the end of a sentence, the second best option is at the beginning.

Form

Use exclamations sparingly, reserve them for true exclamations and commands.
Do not spell out numerals unless they are part of a dialogue
Use italics with capitalized initials for titles of literary work

Style

Work from a suitable design
Write with nouns and verbs
Revise, rewrite, do not overwrite. Diligently strike out words that do not add value to your writing.
Avoid qualifiers such as rather, very, little, pretty
Be clear - avoid fancy words, do not explain too much, do not construct awkward adverbs (tangledly -> in tangles), use orthodox spelling, and avoid shortcuts such as abbreviations unless readily understood

Glossary

Exhaustive glossary is at the end of the book. Following terms are relevant to the notes above.

Appositive - a grammatical construction in which two elements, normally noun phrases, are placed side by side so one element identifies the other in a different way.

My sister, Alice Smith, likes jelly beans.
Participle - a verb form used either as an adjective to modify nouns (“the hidden treasure”) or to connect with auxiliary verbs to create different tenses (“we are hiding the treasure”).
Participial phrase - a modifier that uses the participle to describe a noun (“Walking down the street, he saw kids playing with a ball”).
Preposition - a function word that combines with a noun phrase to form a phrase (“at the dawn”, “by noon”)

The AI Madness

matousdzivjak@gmail.com (Matouš Dzivjak) — Thu, 16 Jan 2025 00:00:00 +0000

I have to rant about the AI mad dash, especially at my place of employment and likely at other places too.

Leadership at our company is reasonable in the capitalistic sense. They optimize for financial gains and disregard human well being (work from the office policy that deserves whole own post). They try to make informed decisions to a varying degree of success but every now and then they catch a Silicon Valley fewer of a cool new tech.

Couple of years back, the next big thing was a bitcoin. I haven’t been with the company at that time but still stumble upon the remains in the code ever so often. And because compared to us - mere mortals - the leadership doesn’t believe in the value of retrospective and learning from past mistakes, the whole bitcoin saga is repeating, except with AI.

The theme of our hack week? AI. Part of our one-sentence goal for 2025? Leverage AI. Theme of the next global all hands? Learnings from last year, new product features, and celebration of successes… who am I kidding, AI.

I don’t rely on AI for writing, the quality isn’t there. Nor do I use copilot or any other code assistant. Occasionally, I ask Chat GPT for a bash script or a hacky code that solves a particular problem that’s outside my expertise and would take me a solid few minutes of googling and reading docs before I even get to writing. There are horses for courses, and AI is helpful for many tasks, from text summaries to quick solutions. Nevertheless, these nuances seem hard to grasp for decision makers at our company and what we have instead, is a migration from Confluence to Notion (“because it has AI”).

The mad AI dash is saddening insight into the whimsy understanding of lower echelons of the company by the C level. From the over the top glorification to the out of touch expectations of its capabilities. We took a technology with a couple of justifiable use-cases and turned it into a solve-it-all wishy-washy machine. No specific plans, no objectives, no metrics. Only a licked finger, stuck into the air, to see where the wind from other companies blows. We made it a solution looking for a problem, while there’s thousands of other problems to solve.

Please, stop shoving AI down our throat, nobody asked for it, and shoving things down our throat certainly violates our code of conduct. The next time I hear “You should use more AI” I am done, man. Let me do my job, let the hands-on experts decide which solution is the best, and if you still wish to throw in AI during the next investor meeting, please find a proper use case first.

No LLM was used while writing this post.

December

matousdzivjak@gmail.com (Matouš Dzivjak) — Wed, 01 Jan 2025 00:00:00 +0000

Coming back from New Zealand I managed to warm up at home (technically cool down, it’s Berlin after all) for 8 days before heading to São Paulo for a tribe off-site. 2025 will be a busy year with multiple large initiatives but the main personal goal of 2024 is to bring SumUp closer to representative state when it comes to developer experience. Our developer website needs a breath of fresh air and robust SDKs for integrators are a must to hide the low quality of our APIs and make it easier to migrate to newer - better - versions in the future.

Frosty leaves during a hike to Lovos, Czech Republic.

Reading

The moon blew up without warning and for no apparent reason.

I finished Neal Stephenson’s Seveneves in 4 days over the Christmas holiday and loved it. Seveneves feels like 2 books in one. First part grounded in the science while the final chapter ventures further into the territory of speculative fiction. The book also leaves just enough loose ends to keep one thinking about it long after while at the same time providing satisfying end. It’s no coincidence that it has an opening sentence that drags you in from the start and the tension doesn’t let you put the book down for next few hundred pages.

This month’s dose of long-form journalism: Masks, Smoke, and Mirrors: The untold story of EgyptAir flight 804 by Kyra Dempsey.

Watching

I got nerd sniped learning more about aviation. After reading the Hard Landing (still in progress) and admiring the magnificence of A380-800 on our way to and from New Zealand I went down the rabbit hole of flight mechanics (e.g. Airfoil by Bartosz Ciechanowski) all the way to How YOU can land a passenger aircraft! 12 steps.

The other deep dive this month was toying with Bevy and learning more about game development. The highlight of which is Rendering Tiny Glades With Entirely Too Much Ray Marching talk by Tomasz Stachowiak, one of the people behind Tiny Glade.

Last but not least, December is the time of the Chaos Computer Club. I am still catching up with the most interesting talks, one that I finished though and enjoyed in particular is Self Models of Loving Grace by Joscha Bach.

And there’s more fun stuff too such as We’ve not been trained for this: life after the Newag DRM disclosure, Hacking yourself a satellite - recovering BEESAT-1, or From Pegasus to Predator - The evolution of Commercial Spyware on iOS.

Listening

Liquicity Year Mix is going on since 2012.

Seveneves

matousdzivjak@gmail.com (Matouš Dzivjak) — Sun, 29 Dec 2024 00:00:00 +0000

Seveneves is an incredibly rich and thrilling speculative fiction by Neal Stephenson. It’s 860 pages long but stays captivating through out, only easing towards the last chapter that could be a standalone novel on its own.

The premise of the book can be summarized by its first sentence which is an opening bang like no other.

The moon blew up without warning and for no apparent reason.

Without revealing too much about the story, Steveneve’s follows humanity’s fight for survival over the course of 5000 years (focusing on a first 5 years for a better part). It manages to combine orbital mechanics and politics in one chapter and continue with robotics and genetics in another one while staying approachable and fun to read.

The story of Seveneves doesn’t shy away from hard topics, deaths, and grim outlooks. It’s a worthwhile albeit lengthy read that makes you travel through time (from 7pm to 2am before you even notice) and yet, it might be one of the few chosen books that require and are worth a second read.

Not the End of the World

matousdzivjak@gmail.com (Matouš Dzivjak) — Sun, 01 Dec 2024 00:00:00 +0000

Hannah Ritchie works at Our World in Data that compiles and publishes datasets on large global problems such as poverty, climate change, diseases, war, or inequality so it shouldn’t come as a surprise that her book Not the End of the World is based in numbers and science. The book is thoughtful and concise journey through 7 major environmental problems - air pollution, climate change, deforestation, food, biodiversity loss, ocean plastics, and overfishing; each chapter explaining current state, how we got there, and what can we do to ensure a sustainable future.

While it’s hard to summarize a book that overflows with a trove of information, there a few underlying concepts and takeaways that stand out. First, while we are under constant barrage of negative news from the outlets, things are in many cases getting better. Civilization is past the peak of deforestation, air quality, or population growth. This doesn’t apply universally, with large discrepancies between first and third world countries, but we (modern countries) are equipped better than every to help countries that are catching up and raising out of poverty.

Secondly, while there’s room for more optimism than many people have, we still need to alter our trajectory in problems such as global warming. Hannah provides suggestions as to how at the end of each chapter and many of the changes have overreaching impact to more than one environmental problem that we are facing. For example, beef consumption contributes to deforestation and water pollution while being the least efficient source of protein (comparing ratios such as water or carbon emissions to gram of protein with other sources). People switching to or lowering their consumption of beef would be a major environmental win.

Lastly, a topic which unfortunately doesn’t get a lot of space in the book, we are at the mercy of policy makers and governments in many regards. It’s important to advocate and vote for people that can make changes higher up and we might just have a chance to be the first truly sustainable generation.

The optimism in Not the End of the World in infectious and reminds me of Enlightement Now by Steven Pinker. On the other hand, there are organizations advocating for policies and laws that align with Hannas ideas but to no avail. The established incentives often contradict what’s best for the planet and fighting against oil companies with billion budgets for lobbying and teams of lawyers on retainer is an uphill battle. I don’t think there is an easy solution and Not the End of the World doesn’t provide an answer either, the best one can do is small steps on personal level and to vote for people that care about the future generations.

If you find these topics interesting Our World in Data has a daily data insight and biweekly digest newsletter that you can subscribe to on ourworldindata.org. Alternatively, both can be accessed as an RSS feed.

November

matousdzivjak@gmail.com (Matouš Dzivjak) — Sun, 01 Dec 2024 00:00:00 +0000

I am back from my 40 day sabbatical in New Zealand. In Some notes on New Zealand I wrote about a few random things that stood out to me but the best story of New Zealand is told by photos. It’s a magnificent country with wonderful people, I wouldn’t mind living there weren’t it so far from pretty much everything.

Kepler Track, New Zealand

Reading

All you need is Wide Events, not “Metrics, Logs and Traces” by Ivan Burmistrov reminded me of Canonical Log Lines 2.0 by Brandur. At SumUp we heavily rely on Open Telemetry but articles such as the above make me want to try and experiment with different approaches. One common painpoint we observe with many teams is the usage of logs. In many cases teams leave everything on info level even in production which results in verbose logs that don’t provide enough useful information to justify their existence and often run into the risk of leaking sensitive data. Furthermore, navigating between different signals (logs, traces, and metrics) is hard unless your company has a strong and enforced guidelines for common attributes (not our case unfortunately).¹

The 2024 United States presidential election is over and people in my little online bubble had a lot to say (rightfully so). Molly White’s Wind the clock rejects the defeatism and focuses on action anyone can take to fight for the press freedom, access to information, and migrant and reproductive rights. In the same vein, Electronic Frontier Foundation pledged “to ensure that technology serves you—rather than silencing, tracking, or oppressing you—does not change” in their The 2024 U.S. Election is Over. EFF is Ready for What’s Next.. Another read-worthy posts include America, the final season and Pluralistic: Antiusurpation and the road to disenshittification.

Observing, even from the safe haven of Europe, one can’t help but feel sad about the lost values, progress thrown away, and the degradation of baseline of what strong leaders should be. David Brooks’s The Road to Character talks about selfless heroes in our history and I wish USA gets back to having their president worth the list.

The ultra-selfish gene by Mathias Kirk Bonde in the Work in Progress news reminded me of The Gene for which I still didn’t finish a write up.

Listening

Viktor Sheen released new album titled Impostor syndrom; as always, the songs are hit or miss with hits frequently ranking in the top 3 of my Spotify yearly recap.

Watching

The 8th longest flight in the world from Auckland to Dubai provides just enough time (17 hours and 25 minutes to be exact) to rewatch the Lord of the Rings trilogy in extended edition. Unfortunately, Emirate’s onboard entertainment had only the theatrical release which had to do. Next month I am flying to Brazil (12 hours to São Paulo) which leaves me with the only other thing on worth re-watching list - Band of Brothers.

For further reading, Scuba: Diving into Data at Facebook is a longer technical dive into the observability infrastructure at Meta. ↩︎

Some notes on New Zealand

matousdzivjak@gmail.com (Matouš Dzivjak) — Wed, 20 Nov 2024 00:00:00 +0000

Yesterday we arrived back from our sabbatical in New Zealand after 5 weeks. I will write a dedicated post about our travels separately, in the meantime, here are a couple observations and appreciation.

Cashless

New Zealand is a truly cashless country. In our 5 weeks we have not taken out cash a single time and paid by card everything everywhere - from coffees, meals and groceries to donations at conservation areas and even food at remote huts. It was freeing; first week or two we were worried about not having any cash at our disposal but by the end of our travels we grew used to it. Our wallets stayed in our bags for better part of our travels as phones were all we needed.

First stop when we got back home to Berlin was to grab a coffee in the morning at Zazza. Their card reader wasn’t working. As a regulars, we were told to pay next time but it made me appreciate the cashless situation in New Zealand. A card reader not working is not the same thing as a place not accepting card payments (the former still being quite common in Europe) but it was a harsh return to reality.

Department of Conservation

Department of Conservation (DOC) is a public service department taking care of conservation of New Zealand’s natural and historical heritage. Their website is one of the best government services/websites I have seen, right there with gov.uk design system. The website provides comprehensive list and map of places to go, things to do, accommodation (huts and lodges) and much more.

We relied heavily on DOC when planning our days for walks, hikes, and places to visit.¹ The website is clean and simple, with all content being straight on point with zero SEO-fluff. A great example of how this looks like is the page for Kepler Track (one of the Great Walks - set of the popular tramping tracks maintained by DOC). At a glimpse the page provides all the information one might need - map, elevation profile, seasonal restrictions, packing list, and more. What is more, there are up to date restrictions (such as closures due to bad weather), direct links to book huts, and for popular tracks even official videos.

I can’t express enough how awesome this is. All the information for hikes and nature one might need, in one place, official. I wish we had something similar in the Czech Republic to make the nature and hikes more accessible to travelers.

Recycling

The general rubbish bins in New Zealand are marked as landfill. It’s a subtle difference but one that I noticed every time we were throwing out trash. I think the difference in wording is a clever way to draw attention to the fact that the trash is here to stay, for years, and nudge more people into recycling. If all trash bins specified where the trash goes (e.g. landfill, recycling plant, or composting plant) maybe we would see more people being thoughtful about recycling.

Plastic recycling in New Zealand is a whole another story unfortunately. The plastic packaging is classified in 5 categories (numbered 1-5) with different categories having different rules. Class 1 and 2 goes into recycling bins. Sometimes we saw recycling bins that specified the classes of plastic that can go in them directly. Class 4 are soft plastics (e.g. empty bag of crisps) and these must be returned back at stores. Unfortunately, not all stores have bins for soft plastics and not all soft plastics can be recycled this way. The whole plastic recycling situation was confusing at best and I hope that next time we go to New Zealand there government will figure out a better approach.

All DOC (Department of Conservation) data is also available via APIs that are directly linked and documented on their website (api.doc.govt.nz). ↩︎

Knowing What We Know

matousdzivjak@gmail.com (Matouš Dzivjak) — Fri, 01 Nov 2024 00:00:00 +0000

Simon Winchester’s Knowing What We Know takes you through history of knowledge from ancient clay tablets through the adoption of GPS to inception of Wikipedia. It’s a thorough examination of how we acquire, pass, and retain knowledge and how has this changed through human history.

I expected deeper scientific examination of cognitive paths related to knowledge processing and retention but Knowing What We Know is rather a historic account and collection of stories and topics on knowledge. It’s a fun read and examination of some of the greatest minds of our history such as Aristotle or Srinivasa Ramanujan but unfortunately falls flat on tying all of its content together.

October

matousdzivjak@gmail.com (Matouš Dzivjak) — Fri, 01 Nov 2024 00:00:00 +0000

This month I learned

Truck Factor (TF) is a tool to identify concentration of knowledge in software development environments. It states the minimal number of developers that have to be hit by a truck (or quit) before a project is incapacitated.¹

Reading

Having more time on my hands this month I spent some time reorganizing my newsletter subscriptions and blogs I follow. Where possible, I switched from email newsletter to RSS feed subscriptions to adopt a pull model (instead of push) for reading. Now my email inbox stays pristine and reading new articles is a deliberate action that requires me to open the Reeder app and refresh subscribed feeds. While at it, I cought up with a few blogs I haven’t read in a while and a lot of open tabs - mostly links from Hacker News. Following is a list of the best picks for this month:

Australia/Lord_Howe is the weirdest timezone fun read and a nice primer to how computers store and resolve time zone data.
We built our house for LAN parties (Show HN: I built a(nother) house optimized for LAN parties) is a teenage-dream come true house setup for LAN parties.
A short story called The Nine Billion Names of God by Arthur C. Clarke.
Machines of Loving Grace by Raegan Bird is a moving read about birth, child loss, and technological interventions.
How I ship projects at big tech companies boils down to ship often and ownership but one highlight that stayed with me is:

a project is shipped when the important people at your company believe it is shipped

Watching

“Performance Matters” by Emery Berger (YouTube) - why performance matters and how to measure it properly.

Listening

In New Zealand we have spent a lot of time driving. I myself don’t mind driving in silence but Iris prefers to have something on so we settled on listening to podcasts. Our current favorite is People I (Mostly) Admire by Steven D. Levitt. Steven brings wide variety of hosts, from book authors to scientists and researchers which makes every podcast unique.

We have gone through 20 episodes during our sabbatical, each unique and fun in its own. Among those that I enjoyed the most is for example episode How to Grow a White Rhino with Thomas Hildebrandt; as German and dry as it gets but wholesome at the same time. The other 2 picks I would highly recommend is Richard Dawkins on God, Genes, and Murderous Baby Cuckoos and The Language of the Universe.

A Novel Approach for Estimating Truck Factors ↩︎

The Gene

matousdzivjak@gmail.com (Matouš Dzivjak) — Mon, 14 Oct 2024 00:00:00 +0000

TODO

July

matousdzivjak@gmail.com (Matouš Dzivjak) — Thu, 01 Aug 2024 00:00:00 +0000

This month I learned

Instrumental convergence

Instrumental convergence is the hypothetical tendency for most sufficiently intelligent, goal directed beings (human and non-human) to pursue similar sub-goals, even if their ultimate goals are quite different. More precisely, agents (beings with agency) may pursue instrumental goals—goals which are made in pursuit of some particular end, but are not the end goals themselves—without ceasing, provided that their ultimate (intrinsic) goals may never be fully satisfied. Best illustrated by captivating Universal Paperclips.

Reading

A Git story: Not so fun this time is a wonderful tour through the history of Git. Reading through I realized how little I know about origins of a technology that I use on daily basis. The most startling realization was how humble the beginnings of it were; Git came to existence as a hack project of Linus Torvals and look where it’s now.

The Time I Built an ROV to Solve Missing Person Cases is a multipart series about an amateur building a ROV (Remotely Operated Vehicle) to solve the disappearance of Jussi Peltola in central Finland.

Watching

I Was An MIT Educated Neurosurgeon Now I’m Unemployed And Alone In The Mountains How Did I Get Here?
Stroads are Ugly, Expensive, and Dangerous (and they’re everywhere) , talking about the negatively impacts of stroads (combination of road and a street) on street life, pedestrian safety, and the look of towns and cities.

Listening

a remix of the 2003 original hit Milkshake by Kelis.

June

matousdzivjak@gmail.com (Matouš Dzivjak) — Mon, 01 Jul 2024 00:00:00 +0000

This month I learned

Shirky Principle, The Shirky Principle: Institutions Try to Preserve the Problem to Which They Are the Solution

Reading

Finished reading The Ministry for the Future, a thrilling mix of science, ecology, and fiction. It’s a hefty book with 576 pages and unique style that works well with its premise.

Watching

Community by Dan Harmon, co-creator of Rick and Morty. It has a slow start but keeps getting better with every season.

The Ministry for the Future

matousdzivjak@gmail.com (Matouš Dzivjak) — Sat, 08 Jun 2024 00:00:00 +0000

The Ministry for the Future is a literal masterpiece, a speculative fiction taking a look at the next 30 years of planet Earth and our effects on it. Scary and sad in its positive outloook that seems every so less likely with where we heading.

Kim Standley Robinson goes into great details of how entangled the whole world is, with money dictating everything else. There are chapters about economics, banking, politics, geoengineering, biology, glaciology, social media, crypto currencies, and more. All written in the most unique style I have seen to date - there are no main characters in The Ministry for the Future; chapters switch between styles from meeting notes, and conversations to essays of science and philosophy.

The Ministry for the Future is a lens into the future, scary and grim all because of us - people, with a dash of hope that requires the stars to align and humanity to change its course before it’s too late.

May

matousdzivjak@gmail.com (Matouš Dzivjak) — Sat, 01 Jun 2024 00:00:00 +0000

I’ve been spending time on side-projects¹ [^esp32], skipping writing, and thus the monthly posts, yet again. A lot has happened in last few months, vacation, races, and more. The only part of this website I managed to tend to are the short posts in the Atoms section which is better suited for random topics and low effort brain dumbs.

Reading

What’s new in CSS and UI: I/O 2023 Edition - some exciting new things comming up, most importantly - CSS nesting! Once the adoption picks up, we won’t need SASS and SCSS tooling everywhere (or so one would hope).
Obituary for a Quite Life
Other people’s problems
What will football look like in the future. I am not even sure what to call this. It’s a short story, wonderful website, it is something… different. Worth the read (and scroll).
We Need To Rewild The Internet
[He Lost $36 Billion in a Week. Now Bill Hwang Is Fighting to Avoid Prison]
Development notes from xkcd’s “Machine” by Max is a writeup of the 15th annual April Fools project by xkcd. The project was a huge Rube Goldberg machine build from submissions of the readers.

Watching

A THOUSAND SUNS - sci-fi short film anthology is a series of youtube videos by A Thousand Suns studio. Similar in concept to Love, Death & Robots with every short film in a completely different settings. For the youtube format, the films are of exceptional quality and I would love to see what could be achieved with similar concept in longer form.

Listening

Sub Focus, Dimension, Culture Shock & 1991 | New York Livestream | WORSHIP x DNBNL x UKF On Air. I wish these sets were on Spotify so I can listen to them on my runs, but I am yet to find justification for paying for YouTube subscription.

Wiki redesign [^esp32] Toying with ESP, briefly summarized in Running Zephyr on ESP32 ↩︎

Death's End

matousdzivjak@gmail.com (Matouš Dzivjak) — Fri, 05 Apr 2024 00:00:00 +0000

Death’s End is the last chapter in the Remembrance of Earth’s Past trilogy by Cixin Liu. I read the first book The Three-Body Problem back in 2021. Returned to the series in 2023 with The Dark Forest and finally decided to read the last book in series after the Netflix adaptation came out.

I was putting Death’s End aside for a long time. The book sat at my office table since I bought it alongside The Dark Forest which I still find the most chilling book I have read to this date. The Three-Body Problem was in my opinion the weakest one in the trilogy (to be clear here, the book is a great read, albeit comparatively weaker to the next 2 in the series). The Dark Forest picked up the pace severely and was a capitative and thrilling read causing the same kind of experience as the border scene from the first Sicario movie.

Parts of Death’s End I have spoiled for myself reading more about the trilogy on the internet. Yet, it enticed me in a way that I finished to book in 2 days. Death’s End brings the story to even grander scale picking up where The Dark Forest left. As with the previous books, it is a capitative read evoking unease from beginning till the end. Now it’s time to wait for how will the Netflix adaptation wrestle with the enormous scale of the book.

March

matousdzivjak@gmail.com (Matouš Dzivjak) — Mon, 01 Apr 2024 00:00:00 +0000

Reading

Almost everyone I’ve met would be well-served thinking more about what to focus on

As a rule of thumb, you can only do 1 or 2 things well. Some people are exceptional: they can do 3. I’m not exceptional.
Commit/bullshit ratio

Everybody does some of it, but the key is ratio. Good engineers do little while pushing features most of the time. Less good engineers engage in a lot of “bullshit”, wasting their own time, and that of others’ who are pulled into reviews and battles.

William Langewiesche’s long form investigative articles rank among my all time favorite reads. Thus, it made me excited when I stumbled upon Call of the Void: Seven years on, what do we know about the disappearance of Malaysia Airlines flight 370? which is a deep dive into the events of 8th of March 2014 when flight MH370 disappeared with all 239 people on board.

Stubborn Attachments

matousdzivjak@gmail.com (Matouš Dzivjak) — Fri, 29 Mar 2024 00:00:00 +0000

TODO

Go PGO

matousdzivjak@gmail.com (Matouš Dzivjak) — Fri, 16 Feb 2024 00:00:00 +0000

Profile-guided optimization is a compiler optimization technique that feeds information (a profile) from representative runs of the application back into to the compiler for the next build of the application, which uses that information to make more informed optimization decisions. It was shipped in a preview version in Go 1.20 and made generally available in Go 1.21.

To use PGO you first need to obtain a profile that ideally matches your live traffic pattern. We do by exposing profiling endpoints internally and grabbing a profile from a running application in kubernetes. We register the profiling endpoints during application startup:

func addPProfHandlers(mux *http.ServeMux) {
	//  "allocs":       "A sampling of all past memory allocations",
	//	"block":        "Stack traces that led to blocking on synchronization primitives",
	//	"cmdline":      "The command line invocation of the current program",
	//	"goroutine":    "Stack traces of all current goroutines",
	//	"heap":         "A sampling of memory allocations of live objects. You can specify the gc GET parameter to run GC before taking the heap sample.",
	//	"mutex":        "Stack traces of holders of contended mutexes",
	//	"profile":      "CPU profile. You can specify the duration in the seconds GET parameter. After you get the profile file, use the go tool pprof command to investigate the profile.",
	//	"threadcreate": "Stack traces that led to the creation of new OS threads",
	//	"trace":        "A trace of execution of the current program. You can specify the duration in the seconds GET parameter. After you get the trace file, use the go tool trace command to investigate the trace.",
	mux.HandleFunc("/debug/pprof/", pprof.Index)
	mux.HandleFunc("/debug/pprof/cmdline", pprof.Cmdline)
	mux.HandleFunc("/debug/pprof/profile", pprof.Profile)
	mux.HandleFunc("/debug/pprof/symbol", pprof.Symbol)
	mux.HandleFunc("/debug/pprof/trace", pprof.Trace)
	mux.Handle("/debug/pprof/heap", pprof.Handler("heap"))
	mux.Handle("/debug/pprof/block", pprof.Handler("block"))
	mux.Handle("/debug/pprof/mutex", pprof.Handler("mutex"))
	mux.Handle("/debug/pprof/goroutine", pprof.Handler("goroutine"))
	mux.Handle("/debug/pprof/threadcreate", pprof.Handler("threadcreate"))
}

Then port-forward the running pod in production:

kubectl port-forward $(kubectl get pods -n identity -o name --no-headers=true | grep 'app-name' | head -n 1) http

And grap a profile by running in another terminal session:

curl -o default.pgo http://localhost:8080/debug/pprof/profile\?seconds=30

That’s it. The go build command will automatically enable pgo if it detects default.pgo file in the root directory. As long as you copy the default.pgo profile into your docker image before the build step there are no additional steps required.

You don’t need to have pprof of the latest change to optimize the binary. It is still good idea to update the profile every now and than, especially after major dependency update or code changes.

From the docs:

Go PGO is generally robust to skew between the profiled version of an application and the version building with the profile, as well as to building with profiles collected from already-optimized binaries. This is what makes this iterative lifecycle possible. See the AutoFDO section for additional details about this workflow.

Source stability is achieved using heuristics to match samples from the profile to the compiling source. As a result, many changes to source code, such as adding new functions, have no impact on matching existing code. When the compiler is not able to match changed code, some optimizations are lost, but note that this is a graceful degradation. A single function failing to match may lose out on optimization opportunities, but overall PGO benefit is usually spread across many functions. See the source stability section for more details about matching and degradation.

The improvements vary from application to application but in the case of our external authorization agent that is called for almost all requests hitting SumUp APIs we have seen improvement in CPU usage and improvement of p50 latency (hotpath) from ~1.5ms to ~0.75ms.

Profile-guided optimization can be a quick performance improvement for your app for a fairly low effort. The improvements wary but PGO can have a drasticall impact on applications that have only a few hot-paths. Lastly, it’s an interesting novelty in the toolset of compiler provided optimizations.

The Design of Everyday Things

matousdzivjak@gmail.com (Matouš Dzivjak) — Wed, 14 Feb 2024 00:00:00 +0000

Notes

Human-centered design - The process that ensures that the designs match the needs and capabilities of the people for whom they are intended
Affordances - relationship between a physical object and a person. E.g. a chair affords support, therefore, affords sitting. A flat plate on a doors affords pushing while a know affords turning, pushing, and pulling. Affordance is jointly determined by the object and the agent that is interacting with it. To be effective, affordance have to be discoverable. Affordance determines what is possible.
Signifiers - Signals presence of affordance. Signifiers communicate where an action afforded by affordance should take place. E.g. a “Push” sign on a door.

The Design of Everyday Things — Book Summary & Notes

December

matousdzivjak@gmail.com (Matouš Dzivjak) — Mon, 01 Jan 2024 00:00:00 +0000

Writing

Reading

Executives certainly make staffing decisions about Platform and Infrastructure teams, but I think they do something even more important: define the company’s engineering strategy. Many companies take a permissive stance towards adopting a variety of technologies, which creates a diffuse approach to internal teams who are supporting too broad a technology landscape. At both Carta and Calm, my most valuable contribution to developer productivity has been constraining allowed technologies, which allows us to concentrate our investment–however large it happens to be–as densely as possible. Will Larson, CTO at Carta and author of the upcoming book The Engineering Executive’s Primer

This month I learned

Ikigai (生き甲斐, lit. ‘a reason for being’) is a Japanese concept referring to something that gives a person a sense of purpose, a reason for living.
Google’s internal code review process:
- Readability: Google’s Temple to Engineering Excellence
- How Google takes the pain out of code reviews, with 97% dev satisfaction
  - Continuous improvement over perfection.
  - Maintain or improve the health of the codebase
  - Follow the Style Guide.
  - Always Share Knowledge.
  - Write Small Changes (<200 LoC).
  - Strict Standards for Lightweightness (reviews under 24h).
  - Politeness and Professionalism
- How Google writes clean, maintainable code
- Critique: Google’s Code Review Tool
- Resolvingcode review comments with ML

Hey computer, what's the time?

matousdzivjak@gmail.com (Matouš Dzivjak) — Sun, 24 Dec 2023 00:00:00 +0000

Hello! This week I read Tony Finch’s Where does my computer get the time from? and decided to learn more about Network Time Protocol (NTP). This is exploration of NTP from scratch.

What Is NTP?

NTP (Network Time Protocol) is a protocol used to synchronize the clocks by hundreds of millions of computers and devices. It’s the protocol that keeps the time accurate on your computer, mobile phone, smart watch, in telecommunication, financial services, and even by Deutsche Bahn albeit with varying accuracy.

The Protocol

On MacOS you can interact with NTP server using the sntp tool:

> sntp time.nist.gov        
+0.084360 +/- 0.155989 time.nist.gov 132.163.96.6

This command returns the time offset (+0.084360 seconds) of local clock from the requested server and the precision (+/- 0.155989 seconds).

Under the hood NTP works over UDP and relies on single datagram for all packets:

 0                   1                   2                   3
 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|LI | VN  |Mode |    Stratum     |     Poll      |  Precision   |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                         Root Delay                            |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                         Root Dispersion                       |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                          Reference ID                         |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                                                               |
+                     Reference Timestamp (64)                  +
|                                                               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                                                               |
+                      Origin Timestamp (64)                    +
|                                                               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                                                               |
+                      Receive Timestamp (64)                   +
|                                                               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                                                               |
+                      Transmit Timestamp (64)                  +
|                                                               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                                                               |
.                                                               .
.                    Extensions and trailers...                 .
.                                                               .
|                                                               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Without extensions, the whole packet fits into 48 bytes. We need only a few lines of code to craft and send a packet on our own:

use std::net::UdpSocket;

fn main() {
    let socket = UdpSocket::bind("0.0.0.0:0").unwrap();

    let request: [u8; 48] = [
        0x23, 0x00, 0x00, 0x00, // LI, VN, Mode, Stratum, Poll, Precision
        0x00, 0x00, 0x00, 0x00, // Root delay
        0x00, 0x00, 0x00, 0x00, // Root dispersion
        0x00, 0x00, 0x00, 0x00, // Reference identifier
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // Reference timestamp
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // Originate timestamp
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // Receive timestamp
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // Transmit timestamp
    ];

    socket.send_to(&request, "132.163.96.1:123").unwrap();
    println!("packet sent!");

    let mut buf = [0; 48];
    let (amt, src) = socket.recv_from(&mut buf).unwrap();
    println!("received {} byte from {}:\n {:?}", amt, src, buf);
}

Let’s break it down, first we need an UDP socket. We bind one on IP address 0.0.0.0 (the default address) and port 0 letting the OS assign the port for us.

use std::net::UdpSocket;

fn main() {
    let socket = UdpSocket::bind("0.0.0.0:0").unwrap();
}

Let’s break it down, first we need an UDP socket. We bind one on IP address 0.0.0.0 (the default address) and port 0 letting the OS assign the port for us.

    let request: [u8; 48] = [
        0x23, 0x00, 0x00, 0x00, // LI, VN, Mode, Stratum, Poll, Precision
        0x00, 0x00, 0x00, 0x00, // Root delay
        0x00, 0x00, 0x00, 0x00, // Root dispersion
        0x00, 0x00, 0x00, 0x00, // Reference identifier
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // Reference timestamp
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // Originate timestamp
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // Receive timestamp
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // Transmit timestamp
    ];

We only need to set first byte of the request. In order:

Leap Indicator (LI) (2 bits) warning of an impending leap second to be inserted or deleted in the last minute of the current month.

+-------+----------------------------------------+
| Value | Meaning                                |
+-------+----------------------------------------+
| 0     | no warning                             |
| 1     | last minute of the day has 61 seconds  |
| 2     | last minute of the day has 59 seconds  |
| 3     | unknown (clock unsynchronized)         |
+-------+----------------------------------------+

Version Number (VN) (3 bits) integer representing the NTP version number, currently 4. Latest version is version 4 from 2012.¹

Mode (3 bits) field indicates the mode of the packet. Client requests have Mode = 3.

+-------+--------------------------+
| Value | Meaning                  |
+-------+--------------------------+
| 0     | reserved                 |
| 1     | symmetric active         |
| 2     | symmetric passive        |
| 3     | client                   |
| 4     | server                   |
| 5     | broadcast                |
| 6     | NTP control message      |
| 7     | reserved for private use |
+-------+--------------------------+

Next we need to actuall send the packet to the NTP server. NTP servers run on port 123. We also need to pick a server to send the packet to. There’s large selection of primary server listed in Overview of popular public NTP servers. We can pick time.nist.gov for example, to avoid plumbing DNS resolution in, we need the IP address though:

> dig +short time.nist.gov
ntp1.glb.nist.gov.
132.163.96.4

Let’s send the pocket:

    socket.send_to(&request, "132.163.96.4:123");
    println!("packet sent!");

There’s last piece missing - obtaining the response from the NTP server. We already have the UDP socket binded, what we need is to receive the response packet.

    let mut buf = [0; 48];
    let (amt, src) = socket.recv_from(&mut buf).unwrap();
    println!("received {} byte from {}:\n {:?}", amt, src, buf);

We can finally run our little NTP example:

> cargo run
   Compiling ntp-rs v0.1.0 (/Users/admin/code/github.com/matoous/ntp.rs)
    Finished dev [unoptimized + debuginfo] target(s) in 1.47s
     Running `target/debug/ntp-rs`
packet sent!
received 48 byte from 132.163.96.1:123:
 [28, 1, 13, 227, 0, 0, 0, 16, 0, 0, 0, 32, 78, 73, 83, 84, 232, 204, 46, 128, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 232, 204, 46, 195, 51, 24, 196, 148, 232, 204, 46, 195, 51, 24, 224, 238]

Slightly underwhelming, but the important stuff is there! We have received an NTP Server response. To decode it, we will first need two helpers:

use std::time::{Duration, SystemTime, UNIX_EPOCH};

fn ntp_duration(val: u32) -> Duration {
    let seconds: u64 = (val >> 16) as u64;
    let fraction: u64 = (val & 0xFFFF) as u64;
    let nanos: u64 = (fraction * 1_000_000_000) / 65536;
    Duration::new(seconds, nanos as u32)
}

fn ntp_timestamp(val: u64) -> SystemTime {
    let seconds_since_ntp_epoch = (val >> 32) as u64;
    let seconds_since_unix_epoch = seconds_since_ntp_epoch - 2_208_988_800;
    let fractional_seconds = (val & 0xFFFFFFFF) as u64;
    let nanos = (fractional_seconds * 1_000_000_000) >> 32;
    UNIX_EPOCH + Duration::new(seconds_since_unix_epoch, nanos as u32)
}

NTP timestamps use offset from 1 Jan 1900 as compared to Unix time that uses January 1, 1970. This requires some manipulation on our side to convert to time types from Rust standard library.²

With these two helpers we are equipped to parse the whole response:

let leap_indicator = buf[0] >> 6;
let version = (buf[0] & 0b00111000) >> 3;
let mode = buf[0] & 0b00000111;
let stratum_level = buf[1];
let polling_interval = buf[2];
let precision = buf[3];

let root_delay = ntp_duration(u32::from_be_bytes(buf[4..8].try_into().unwrap()));
let root_dispersion = ntp_duration(u32::from_be_bytes(buf[8..12].try_into().unwrap()));
let reference_id = std::str::from_utf8(&buf[12..16]).unwrap();
let reference_timestamp = ntp_timestamp(u64::from_be_bytes(buf[16..24].try_into().unwrap()));
let receive_timestamp = ntp_timestamp(u64::from_be_bytes(buf[32..40].try_into().unwrap()));
let transmit_timestamp = ntp_timestamp(u64::from_be_bytes(buf[40..48].try_into().unwrap()));

and all that’s left is to print the data for our amusement:

println!("received {} byte from {}:\n {:?}", amt, src, buf);
println!(
    "leap indicator: {}, version: {}, mode: {}",
    leap_indicator, version, mode
);
println!("stratum level: {:x?}", stratum_level);
println!("polling interval: {}s", 2_i32.pow(polling_interval as u32));
println!("precision: {}s", 2_f32.powf(precision as i8 as f32));
println!("root delay: {:?}", root_delay);
println!("root dispersion: {:?}", root_dispersion);
println!("reference ID: {:?}", reference_id);
println!("reference timestamp: {:?}", reference_timestamp);
println!("receive timestamp: {:?}", receive_timestamp);
println!("transmit timestamp: {:?}", transmit_timestamp);

Running our Rust script again should yield something like:

> cargo run
    Finished dev [unoptimized + debuginfo] target(s) in 0.00s
     Running `target/debug/ntp-rs`
Packet sent!
received 48 byte from 132.163.97.6:123:
 [28, 1, 13, 227, 0, 0, 0, 16, 0, 0, 0, 32, 78, 73, 83, 84, 232, 204, 237, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 232, 204, 237, 28, 136, 29, 211, 186, 232, 204, 237, 28, 136, 29, 239, 234]
leap indicator: 0, version: 3, mode: 4
stratum level: 1
polling interval: 8192s
precision: 0.0000000018626451s
root delay: 244.14µs
root dispersion: 488.281µs
reference ID: "NIST"
reference timestamp: SystemTime { tv_sec: 1696755328, tv_nsec: 0 }
receive timestamp: SystemTime { tv_sec: 1696755356, tv_nsec: 531705124 }
transmit timestamp: SystemTime { tv_sec: 1696755356, tv_nsec: 531706804 }

We can also verify that the timestamps match our expectations by converting them to human readable string:

> date -r 1696755356      
Sun Oct  8 10:55:56 CEST 2023

In the example above you can notice that we use SystemTime, system time is a clock maintained by the hardware and operating system while the frequently used Coordinated Universal Time (UTC) timescale represents mean solar time as specified by national standards laboratories. The goal of NTP is to minimize the time difference between UTC and the system clock.

Notes

There’s also RTP (Rough Time Protocol) addressing some issues with NTP such as security and bootstrapping client with 0 knowledge of time. You can check an opensource implementation by Cloudflare - cloudflare/roughtime.

For fully functioning NTP rust implementation see pendulum-project/ntpd-rs.
chrony is one of the popular OS NTP implementations.

November

matousdzivjak@gmail.com (Matouš Dzivjak) — Fri, 01 Dec 2023 00:00:00 +0000

After a year I got back to contributing to Helix. Firstly, by finishing the long forgotten feat(commands): open urls with goto_file command pull request that enables links in the document to be opened using the Goto file functionality.

In Add modus operandi themes Alexis Mousset ported the light Modus Themes packaged by default with GNU Emacs. The dark Modus Theme caught my eye as they seem to be close to what I was looking for for a long time. The theme is accessible, conforming with the highest standard for colour contrast between background and foreground values (WCAG AAA), and still maintains fresh look. In feat(themes): add modus vivendi theme(s) I ended up porting all the dark themes hoping this will finally resolve my dissatisfaction with most other themes.

I have also another long-open PR that implements LSP Code Lens.

I left this site unattained for a long time spending most of my free time working on the more interesting topics from my job and doing sports.

Writing

I have spent time exploring and writing about NTP building a little example in [Rust]. The whole journey was started by the Where does my computer get the time from? presentation by Tony Finch. I wanted to spend more time on the NTP implementation and implement tiny NTP server but fell down the rabbit hole of parsing binary data into Rust structs. If the time permits, I would like to revisit this topic in the future.

Reading

Awareness at Death
Plastic Money
Theory of Interstellar Trade
Alice and Bob Meet the Wall of Fire by [Thomas Lin](Thomas Lin) explores core topics of modern physics from general relativity to the theory of increasing entropy and the string theory. It’s a hard, intense, but interesting read outlining the most important discoveries and theories from the world of physics in 20th and 21st century. Thomas Lin is the Editor in Chief at Quanta Magazine and his knowledge shows, Alice and Bob Meet the Wall of Fire was a worthwhile read.

Listening

Absolute banger from the new album 2 RUFF, Vol. 1 by Chase & Status.

October

matousdzivjak@gmail.com (Matouš Dzivjak) — Wed, 01 Nov 2023 00:00:00 +0000

Bosnia was a blast, from nature, to food and cities. I squeezed in a couple long runs, preparing for next season. We have spent the first half in national parks, traveling from Banja Luka all the way down to Mostar. Last couple of days we have spent in Sarajevo and surroundings. Bosnia’s nature was astounding and one can just wonder, how further could have it been be it not for the events at the brink of the century.

The rest of October was mostly in the name of work, except one weekend that we’ve spent we siblings in Berlin, welking, eating, sightseeing.

Reading

Listening

Viktor Sheen released new album, yet again in completely different style. As always, I found only 2-3 songs that I enjoyed on the first listen but expect to some more to grow on me as the time goes.

September

matousdzivjak@gmail.com (Matouš Dzivjak) — Tue, 03 Oct 2023 00:00:00 +0000

I missed this month and am backfilling a few notes with a large lag. In September we had a company hack-week in Bulgarie, continuing our work on the developer portal that we started last year. We added self-provisioning of test accounts, rewrote the website in Astro, and added custom rendering of OpenAPI specs.

At the end of the month we flew to Bosnia for a 10 day vacation.

Reading

Where does my computer get the time from? - slides from a talk about computer time and NTP. Computers have precise time thanks to a chain going from NTP Servers, satellites, all the way to US Naval Observatory, atomic clocks, and a lot of scientist making sure that clock stay in sync with actual earth position.
- NTP
- PTP

This month I learned

Goodhart’s law - “When a measure becomes a target, it ceases to be a good measure”.

Listening

The Dark Forest

matousdzivjak@gmail.com (Matouš Dzivjak) — Thu, 21 Sep 2023 00:00:00 +0000

The Dark Forest is the second book in the Remembrance of Earth’s Past series by Liu Cixin. The book is the origin of the Dark forest hypothesis, one of the possible solutions to the Fermi paradox.

The Dark Forest builds on the first book - The Three-Body Problem but in a grand scale spanning a time-frame of 300 years between the events at the end of The Three-Body Problem and the first contact with Trisolaran fleet. As in the first book, The Dark Forest is heavily based in science touching on other topics such as sociology and politics.

The Dark Forest is a nail-bitting read, thrilling from beginning to the end and one of the fiction books that made it on my Devaured under 3 days books list.

June

matousdzivjak@gmail.com (Matouš Dzivjak) — Sat, 01 Jul 2023 00:00:00 +0000

June was a rollercoaster, from failed Ironman to fun weekend in Prague with friends from Berlin.

I haven’t learned my lesson for 3rd time and inflamed my soleus after buying new running shoes and Birkenstocks and not easing into them well enough. Now writing this with 7 days left before another attempt at Ultratrail Val d’Aran and not being able to properly train the last couple days.

Writing

The Wiki page on Writing grew quite a lot and I found a plenty of interesting resources from University of Minnesota - Style Manual to the US Federal plain language guidelines. The interest in writing came again with multiple ongoing RFCs at work and miserable attempts of fighting psychological load by putting thoughts into words.

Common Bugs in Writing is a concise list of the most common bugs in technical writing. It seems to follow closely takeaways from the aforementioned resources as well as books such as On Writing Well or Sense of Style.

What all sources agree on is: Know what you are writing about and why and Be concise, strong, and clear.

Note taking

I still struggle to find the right tool and approach to note-taking, knowledge retention, and bookmarking. My wish would be to maintain all of these in one place, but no tool so far seems to do exactly what I would like.

Notion is the closest I got to ideal setup. The UI is clean, it supports exports into Markdown (albeit not great), and there’s integrated search. On the other hand, it doesn’t work that well for bookmarking. One alternative that I haven’t tried at is ClickUp with extensive list of features and support for integrations and apps (such as tags).

For knowledge the wiki is working great, I like the simplicity of markdown files and being able to edit straight from the command line. What I miss though is being able to tag and full-text search all the collected links. As far as I am aware there’s no tool that would support this (maybe some bookmarking tools do?).

One day I might try to build a thing of my own; backed by markdown files, with simple web UI and search, self-hosted, and persisted in GitHub. The flatnotes UI looks good and close to the goal (exaplained in details in I built a perfect note taking system blog post).

Reading

Accountability for Effective Teams - the important part of accountability is about behaviour, accountability tied to measurable outcomes might focus on things that people don’t have under their control. Accountability is about being able to explain yourself and to care.

This accountability-to-understand is compatible with systems in ways that accountability-for-outcomes is not. If your job depends on moving a number, you’ll move that number, even if it puts your widget in everyone’s way and pisses off customers. If your job depends on the whole business succeeding with your contributions, then you’ll make your widget compatible with its surroundings, and highlight it in ways that improve the product.

Full Time - on quiting a job and going full time on a side-project.
Bits about Money by Patrick McKenzie (advisor at Stripe)
On the Value of Not Reaching Your Goals by Simone Stolzoff
The HN discussion under Demystifying burnout – A deep dive into its symptoms and remedies

This month I learned

There’s new Payment Request API standardization by W3C that seems to be close (API wise) to WebAuthn and looks promising.

Dark forest hypothesis is one of the possible solutions to the Fermi paradox.

The dark forest hypothesis is the conjecture that many alien civilizations exist throughout the universe, but they are both silent and paranoid.

Listening

Kanine’s latest set is fire and I had it on repeat for most of the month:

Last episode of People I (Mostly) Admire by Steven Levitt with Talithia Williams was a joyful listen on one of the long car rides.

On Writing Well

matousdzivjak@gmail.com (Matouš Dzivjak) — Fri, 23 Jun 2023 00:00:00 +0000

Writing is strongest when it’s simple and clear of clutter.
Make every sentence do useful work.
Always be yourself. Warmth and humanity are the two most important qualities of good nonfiction writing.
Leave the reader with one provocative thought that they didn’t have before.
Understated humor is the nonfiction writer’s secret weapon.

May

matousdzivjak@gmail.com (Matouš Dzivjak) — Thu, 01 Jun 2023 00:00:00 +0000

Our (SumUp) API documentation and developer portal is subpar and unfortunatelly not getting a too much attention. Last hackweek, at this ponit almost year ago, we reworked the portal using Docusaurus and Docusaurus OpenAPI Doc Generator. Now I am spending time on Developer portal 2.0, this time built on top of Astro with custom OpenAPI rendering. It’s an entertaining sideproject. Rendering OpenAPI specs doesn’t seem that hard (as long as your OpenAPI specs are in a good shape, which for us isn’t exactly the case). Furthermore, I testing out ChatGPT for rewriting React components into Astro and it is working pretty well. Rewriting and updating existing code seems to be a task well suited for it.

While we are taking out the dirty laundry, another broken thing at SumUp is the RFC process. Although, I am not sure if something that’s absent can be broken. We set to fix this by creating an RFC process and working group inspired by The Power of “Yes, if”: Iterating on our RFC Process and Oxide’s RFD 1 Requests for Discussion. If there’s an initiative that I would love to succeed it’s this one. RFCs for cross-tribe and cross-team agreement in an organisation of 700 engineers are a must and we are suffering greatly from not having a process.¹

Reading

Contrafreeloading

The three grand essentials of happiness are: Something to do, someone to love, and something to hope for.
Lean = fast from Brandur on speed of delivery, the power of small teams, uniform tech stack, and services of reasonable size.
Animated Drawings, implementation of the algorithm described in the paper ‘A Method for Automatically Animating Children’s Drawings of the Human Figure’.

This month I learned

Watching

Listening

There are other great resources concerning this topic such as Scaling Engineering Teams via RFCs: Writing Things Down by Gergely Orosz. ↩︎

How the World Really Works

matousdzivjak@gmail.com (Matouš Dzivjak) — Thu, 18 May 2023 00:00:00 +0000

A realistic grasp of our past, present, and uncertain future is the best foundation for approaching the unknowable expanse of time before us. While we cannot be specific, we know that the most likely prospect is a mixture of progress and setbacks, of seemingly insurmountable difficulties and near-miraculous advances. The future, as ever, is not predetermied. Its outcome depends on our actions.

Vaclav Smil deserved second chance after I gave up on Growth. How the World Really Works was just as dense as Growth but focused on broader topic and as such, felt more accessible. The first few chapters explain the history and current state of the fundamental things of modern world: energy, food production, materials, and globalization. Next chapters focus on present happenings and future outlooks, specifically in regards to the environment.

Vaclav’s writing is objective and grounded in science. The book is written with high degree of agnosticism and Vaclav specifically avoids making any predictions about the future and provides whole few pages of examples of how miserably we fail to predict anything even remotely distant.

How the World Really Works was a heavy, saddening but also prospective, and informative read. What I am taking away is that we should focus more on preventing food waste. Furthermore, any progress even if drastic that we make in ecology today will take tens of years to show, yet we are deciding about the future of billions of people.

we are a fossil-fueled civilization whose technical and scientific advances, quality of life, and prosperity rest on the combustion of huge quantities of fossil carbon, and we cannot simply walk away from this critical determinant of our fortunes in a few decades, never mind years

Notes

due to power density it is highly unlikely that our prime movers (trucks, ships, planes) will switch away from fossil-fuel for power
fossil-fuels are also heavily utilized (and irreplaceably so) in food production (from powering the machinery to fertilizers synthetization)
energy consumption is closely tied to economic growth

Food

enourmous amount of food in modern world is wasted, large contribution to ecology would be reducing the waste
food production requires large qunatity of fossil fuelds, Vaclav provides a few examples where he converts food to the direct amount of fueld used for the production (e.g. for 1kg of bread it is around 250ml of fossil fuel)

The Four Pillars of Modern Civilization

ammonia (used as artificial fertilizer)
plastic
steel
concrete

all are energy-intensive to produce, only plastic and ammonia require fossil fuels as feedstock
all produced in staggering qunatities (hundreds of millions to billions of tons annually)
we don’t have suitable alternatives for any of it

Climate change

public discourse around climate change gravitates towards extremes of either techno-optimism or catastrophism
catastrophists tend to be wrong all the time
techno-optimists rarely understand the underlying constraints of modern world
we are rightfully worried, at the same time throughout the history we always found a solution (so far)
Smil also gives very grimm outlook to all the recent initiatives, most national and international agreements empty promises without commitment
furthermore, as mentioned above, we can’t move away from fossil fuelds for plastic and ammonia anytime soon and even for transportation we are far from having an alternative
rapid decarbonization could only be achieved by making sacrifices utterly impalatable to the vast majority of people
the problem of delayed gratification - even drastic reductions to emissions “will not show any convincing benefits for decades”

everything you thought you knew, and why you’re wrong, review by Nathaniel Rich

Tiny Habits

matousdzivjak@gmail.com (Matouš Dzivjak) — Thu, 18 May 2023 00:00:00 +0000

TODO

April

matousdzivjak@gmail.com (Matouš Dzivjak) — Mon, 01 May 2023 00:00:00 +0000

This month I ran Istria100 ultra-trail race in Croatia. I wasn’t feeling 100% the week before, mostly due to stomach issues where I didn’t feel well after consuming literally anything. Luckyli, everything got better day before the race and I felt strong coming to the start line.

The race went exceptionally well. At 30km my quads showed a little sign of cramps and tear that quickly went away. At Kullamannen half a year ago this is where they started to hurt and didn’t stop until the end of the race. The focus was first to reach the 45km aid station feeling well (did so), then to reach the 80th kilometer in a reasonable shape and time (this also worked out) after which the rest of the race was flat or downhill. I learned my lesson in previous races and spent more time on the aid stations, mostly stuffing myself with salty things - from crackers to soup. My dumb self a year ago didn’t want to believe that cheese and bacon are reasonable snacks to have during an ultra trail run but damn, do they help to calm down the stomach otherwise full of isotonic drinks and carbohydrate gels.

I finished race in 13:59:29 on 40th place out of 387 with the final stats showing 110km and 4200m of elevation gain. I am beyond satisfied, now back to training for Ironman Hamburg and Ultratrail Val d’Aran.

＊

Lifeclub is a wonderful learning website for life skills, the skills they won’t teach you at school yet can improve your life tremendously - effective communication, emotional intelligence, resilience, self-knowledge, people management, money management, and more.

Reading

The Gambler Who Beat Roulett - long form article about mathematicians that beat the rulet by exploiting imperfections of the spinning wheel and the ball.
Grid World
The age of average
Carl Braun on Communicating Like a Grown-Up
Bicycle by Bartosz Ciechanowski
The Kids are Not Okay
Be a thermostat, not a thermometer

This month I learned

Need for cognition

The need for cognition (NFC), in psychology, is a personality variable reflecting the extent to which individuals are inclined towards effortful cognitive activities.

Need for cognition has been variously defined as “a need to structure relevant situations in meaningful, integrated ways” and “a need to understand and make reasonable the experiential world”. Higher NFC is associated with increased appreciation of debate, idea evaluation, and problem solving. Those with a high need for cognition may be inclined towards high elaboration. Those with a lower need for cognition may display opposite tendencies, and may process information more heuristically, often through low elaboration.

Watching

The Last of Us.

Listening

The Road to Character

matousdzivjak@gmail.com (Matouš Dzivjak) — Wed, 05 Apr 2023 00:00:00 +0000

Notes

Two opposing sides of our natures:

Adam 1
- career-oriented, ambitious side of our nature
- wants to have high status and win victories
Adam 2
- wants to embody mora qualities
- a quiet but solid sense of right and wrong, not only to do good, but be good
- wants to have cohesive inner sould

Takeaways

Roughly rephrased takeways from the last chapter of the book:

We don’t live for happiness, we live for holiness

we seek to live live of purpose, righteousness, and virtue, not just for pleasure
best life is oriented around excellence of the soul, moral joy, gratitued, and tranquillity

The above proposition defines the goal of live

road to character begins by understanding our nature
the core being that we are flawed - tendenecy toward selfishness and overconfidence

In the struggle against your own weakness, humility is the greatest virtue

humility is having accurate assesment of our nature and place in the world

Pride is the central vice

pride blinds us to our weaknesses, makes us more certain and closed-minded, makes us more coldhearted, and deludes us into thinking we are authors of our own lifes
because of pride we try to prove that we are better than those around us

Once the necessities for survival are satisfied, the struggle against sin and for virtue is the central drama of live

winning is not possible, the goal is to get better at waging the moral war
there are heroes and schmucks in all parts of world

Character is built in the course of your inner confrontation

one does become more disciplined, considerate, and loving through a thousand small acts of self-control, sharing, and friendship
character is about engraving certain tendencies into our mind

The things that lead us astray are short term - lust, feat, vanity, gluttony
The things the compose character are long term - courage, honesty, humility
No person can achieve self-mastery on their own
Defeating wekness often means quieting the self

the struggle against wekness requires reticence and modesty, muting our own ego

Wisdom emerges out of a collection of intellectual virtues

knowing how to behave when perfect knowledge is lacking, which is almost always

No good life is possible unless it is organized around a vocation

vocation is not found by looking within but by asking what life is asking of us

Maturity is achieved by being better than you used to be, it is not comparative

March

matousdzivjak@gmail.com (Matouš Dzivjak) — Sat, 01 Apr 2023 00:00:00 +0000

Another few days of cycling in Spain, then back home, a week of work, and we left for back-country skiing in Slovakia. After hectic January and February I was looking forward being back in Berlin and on my regular schedule. And brunches, I was really missing brunches.

We thought of life by analogy with a journey, a pilgrimage, which had a serious purpose at the end, and the thing was to get to that end, success or whatever it is, maybe heaven after you’re dead. But we missed the point the whole way along. It was a musical thing and you were supposed to sing or to dance while the music was being played. The Wisdom of Insecurity by Alan Watts

Reading

Quitting the Rat Race - just give it a read, it’s short.

In times like these every signal is telling me to stay on the path I’m on, enjoying the comfort and safety of a high paying job. I’m not going to listen. I’m quitting and I’m leaving this place. I’ll see you in the mountains.
Steve Wozniak used to tip from printed sheets of $2 bills

As I opened my wallet, I considered whether I should risk using this fake ID on the Secret Service. It probably amounted to a real crime. I had my driver’s license as well. But you only live once and only a few of us even get a chance like this once in our lives. So I handed him the fake ID. He noted and returned it. The Secret Service took an ID that said “Laser Safety Officer” with a photo of myself wearing an eyepatch.
Everything You Can’t Have

I wrote a blog post titled How do CloudFlare Workers work? about CloudFlare Workers.

Watching

The Last of Us. New episodes still hold the quality high and I am grateful I found something interesting to watch after a long time.

Listening

Got introduced to the Hilltop Hoods by Jakub and I found a few songs that I really enjoyed. Others not so much, but this one I had on repeat for great part of the month.

How do CloudFlare Workers work?

matousdzivjak@gmail.com (Matouš Dzivjak) — Wed, 08 Mar 2023 00:00:00 +0000

V8 Isolates is the cool tech behind CloudFlare Workers. The same technology powers Deno Deploy, Fastly Compute@Edge, Vercel Serverless Functions, and more. Isolates are lightweight contexts that encapsulate application data (variables and code). V8, the underlying javascript and WebAssembly engine, then ensures that isolates are executed in a safe and isolated environment.

Let’s take a look at how CloudFlare workers work by creating minimal serverless functions runtime in Rust.

Hello world

Before we dive deeper we will start with the pinnacle of engineering, the Hello World program. Even though this is the longest Hello World you have ever seen we aim to illustrate one important thing: the V8 engine does most of the heavy-lifting for us.

We will bootstrap our application by running¹

cargo new hello_isolate && cd hellow_isolate

Before we can create our first Isolate and the Hello World! application we will need to add our first dependency - V8. V8 is written in C++, the V8 cargo package provides Rust bindings.

cargo add v8

Lastly, we modify the src/main.rs file to run our Hello World! application as a V8 Isolate.

use v8;

fn main() {
    let platform = v8::Platform::new(0, false).make_shared();
    v8::V8::initialize_platform(platform);
    v8::V8::initialize();

    let isolate = &mut v8::Isolate::new(v8::CreateParams::default());

    let handle_scope = &mut v8::HandleScope::new(isolate);
    let context = v8::Context::new(handle_scope);
    let scope = &mut v8::ContextScope::new(handle_scope, context);

    let code = v8::String::new(scope, "'Hello' + ' World!'").unwrap();
    let script = v8::Script::compile(scope, code, None).unwrap();

    let result = script.run(scope).unwrap();

    let result = result.to_string(scope).unwrap();
    println!("{}", result.to_rust_string_lossy(scope));
}

Now the magic, run the code and observe:

cargo run

   Compiling lazy_static v1.4.0
   Compiling bitflags v1.3.2
   Compiling v8 v0.63.0
   Compiling hello_isolate v0.1.0 (/Users/mat/code/github.com/matoous/hello_isolate)
    Finished dev [unoptimized + debuginfo] target(s) in 8.45s
     Running `target/debug/hello_isolate`
Hello World!

Not very impressive, is it? Let’s break down the code and explain what’s happening.

let platform = v8::Platform::new(0, false).make_shared();
v8::V8::initialize_platform(platform);
v8::V8::initialize();

Platform::new(0, false) creates new platform. The 0 if for the thread pool size. We can either specify the number of threads the V8 platform will use or pass 0 to let the V8 select the best option based on the number of available processors. The second attribute is used for enabling idle task support which we leave disabled. V8::initialize_platform(platform) initializes the platform and V8::initialize() initializes the V8 engine itself.

With these 3 lines we have bootstrapped the V8 engine and are ready to run out first isolate.

let isolate = &mut v8::Isolate::new(v8::CreateParams::default());
let handle_scope = &mut v8::HandleScope::new(isolate);
let context = v8::Context::new(handle_scope);
let scope = &mut v8::ContextScope::new(handle_scope, context);

With v8::Isolate::new we create new instance of an V8 isolate that will be used to run our script. Isolate is the primitive of sandboxing user scripts. v8::CreateParams allow us to specify additional parameters for the Isolate such as mechanism for recording statistics or limiting the memory consumption by imposing maximum on the heap size.

HandleScope handles data for specific isolate and Context is used for the isolate execution. By calling ContextScope::new(handle_scope, context); we enter the newly created context and can compile and run our script.

let code = v8::String::new(scope, "'Hello' + ' World!'").unwrap();
let script = v8::Script::compile(scope, code, None).unwrap();

String::new allocates a new string with our code within the specific scope. And by calling Script::compile(scope, code, None) we compile our JavaScript code. The code will be tied to the specific scope.

let result = script.run(scope).unwrap();
let result = result.to_string(scope).unwrap();
println!("{}", result.to_rust_string_lossy(scope));

At last we run our script. We again need to pass in the same scope that we used for compilation. run() returns arbitrary (untyped) Value, before we use it we need to cast it to string. In rust this requires two calls. One .to_string call on the Value to convert the value to JavaScript string and the other .to_rust_string_lossy call to convert the JavaScript string to Rust string that we can use within our program.

Here’s repository for the whole Hello World! application.

Runtime

Hello world is neat, but one does not build a product on top of hello world. To get something useful out of the Isolates we need runtime. Runtime provides the well known JavaScript APIs that we are used to, such as fetch or Web Crypto.³

Let’s rework our example by providing runtime for the scripts, shall we? And while at it, we will move from script towards the notion of a worker that exposes handler function that can be repeatedly called by our application.

First, we will create a helper function that will setup the runtime by creating bindings. Bindings allow us to call Rust functions from the JavaScript code of the worker.

fn setup_runtime(isolate: &mut v8::OwnedIsolate) -> v8::Global<v8::Context> {
    let isolate_scope = &mut v8::HandleScope::new(isolate);
    let globals = v8::ObjectTemplate::new(isolate_scope);
    let resource_name = v8::String::new(isolate_scope, "sayHello").unwrap().into();
    globals.set(
        resource_name,
        v8::FunctionTemplate::new(isolate_scope, say_hello_binding).into(),
    );
    let global_context = v8::Context::new_from_template(isolate_scope, globals);
    v8::Global::new(isolate_scope, global_context)
}

Our setup_runtime function will take the Isolate, create an object for globals on which we will define our runtime APIs, and return a Context with the runtime that can be used for the code execution.

pub fn say_hello_binding(
    scope: &mut v8::HandleScope,
    args: v8::FunctionCallbackArguments,
    mut retval: v8::ReturnValue,
) {
    let to = args.get(0).to_rust_string_lossy(scope);
    let hello = v8::String::new(scope, format!("Hello {}!", to).as_str())
        .unwrap()
        .into();
    retval.set(hello);
}

We have defined single runtime function called sayHello. Above we have its Rust binding. The function takes the first argument (expecting it to be a string) and returns new string with Hello {argument}!.

Next, we will create a function for building our worker. In the initial Hello World example we simply executed the provided script. What we want to do instead is compile the worker as a module and call a handler function that it exports.

fn build_worker(
    script: &str,
    worker_scope: &mut v8::HandleScope,
    global: &v8::Global<v8::Context>,
) -> v8::Global<v8::Function> {
    let code = v8::String::new(worker_scope, script).unwrap();
    let resource_name = v8::String::new(worker_scope, "script.js").unwrap().into();
    let source_map_url = v8::String::new(worker_scope, "placeholder").unwrap().into();
    let source = v8::script_compiler::Source::new(
        code,
        Some(&v8::ScriptOrigin::new(
            worker_scope,
            resource_name,
            0,
            0,
            false,
            i32::from(0),
            source_map_url,
            false,
            false,
            true,
        )),
    );
    let module = v8::script_compiler::compile_module(worker_scope, source).unwrap();
    module.instantiate_module(worker_scope, |_, _, _, _| None);
    module.evaluate(worker_scope);

    let global = global.open(worker_scope);
    let global = global.global(worker_scope);
    let handler_key = v8::String::new(worker_scope, "workerHandler").unwrap();
    let js_handler = global.get(worker_scope, handler_key.into()).unwrap();
    let local_handler = v8::Local::<v8::Function>::try_from(js_handler).unwrap();
    v8::Global::new(worker_scope, local_handler)
}

build_worker function compiles the worker as a module, instantiates it, evaluates the module and its dependencies, and finally obtains global reference to the workerHandler function from the module that we can call outside the local context of the script.

Last missing part in this puzzle is executing our worker (calling the exported handle function). For that we will define run_worker function that takes the worker, V8 execution scope, and reference to the global context.

pub fn run_worker(
    worker: v8::Global<v8::Function>,
    scope: &mut v8::HandleScope,
    global: &v8::Global<v8::Context>,
) {
    let handler = worker.open(scope);
    let global = global.open(scope);
    let global = global.global(scope);

    let param = v8::String::new(scope, "World").unwrap().into();
    match handler.call(scope, global.into(), &[param]) {
        Some(response) => {
            let result = v8::Local::<v8::String>::try_from(response)
                .expect("Handler did not return a string");
            let result = result.to_string(scope).unwrap();
            println!("{}", result.to_rust_string_lossy(scope));
        }
        None => todo!(),
    };
}

With this setup we expect our worker, that is the handler that it exposes, to accept a string as a parameter and return a string. In CloudFlare Workers or Deno deploy your function would usually be called with a Request and would be expected to return a Response.

Now we put all of the above together to have a complete example.

fn main() {
    let platform = v8::Platform::new(0, false).make_shared();
    v8::V8::initialize_platform(platform);
    v8::V8::initialize();

    let runtime = include_str!("runtime.js");

    let worker_script = r#"
export function handler(y) {
    return sayHello(y);
};
"#;

    let script = format!(
        r#"
{runtime}
{worker_script}
"#
    );

    {
        let mut isolate = v8::Isolate::new(v8::CreateParams::default());
        let global = setup_runtime(&mut isolate);
        let worker_scope = &mut v8::HandleScope::with_context(isolate.as_mut(), global.clone());
        let handler = build_worker(script.as_str(), worker_scope, &global);
        run_worker(handler, worker_scope, &global);
    }

    unsafe {
        v8::V8::dispose();
    }
    v8::V8::dispose_platform();
}

The script that we compile consists of JavaScript runtime provided by us and the worker script that would in real world scenario be provided by the user. Our javascript runtime is 3 lines of code the help us expose the provided handler from the global scope.

globalThis.workerHandler = (x) => { 
    return handler(x)
}

We can run our application again with the above changes a get a underwhelming:

   Compiling hello_isolate v0.1.0 (/Users/admin/code/github.com/matoous/hello_isolate)
    Finished dev [unoptimized + debuginfo] target(s) in 2.17s
     Running `target/debug/hello_isolate`
Hello World!

This is as far from production ready as it gets but at this point we have shown the very basics of serverless JavaScript execution. In short, serverless javascript is executed in lightweight Isolates that ensure that the worker has access only to its own code and data. Servers that run the workers are responsible for providing runtime and running the isolates.

Wrap

If I did well enough, this article illustrates that at the core serverless JavaScript execution using the V8 engine isn’t complex. Most of the work is providing specification-compliant runtime APIs and implementing and operating the server itself. CloudFlare workers provide additional features such as automatically providing their other products in the runtime⁴ (KV, R2).

Big part of serveless JavaScript that we completely skipped here is the security. I don’t have enough knowledge to share more on that topic but CloudFlare has a Mitigating Spectre and Other Security Threats: The Cloudflare Workers Security Model blog post that dives into this topic and further illustrates the setup used by CloudFlare workers.

CloudFlare opensourced their workers runtime 4 years after their first announcement of Workers. Deno itself has a guide on creating your own JavaScript runtime that uses the Deno crate that hides a lot of the complexities of V8 behind clean API. Another open-source implementation is lagon, a fairly new project that has many features yet is still easy to read.

Furthermore, if Rust is not your language of choice you can try and replicate the Hello World! application in Go using github.com/rogchap/v8go.

You can find the whole Hello World! example at github.com/matoous/hello_isolate and the second part with runtime under the hello-runtime branch.

Keep in mind that this was written to the best of my knowledge and there might be factual mistakes, bugs, or completely neglected topics. If you find any of such, please let me know. Points of contact and GitHub link to this file are in the footer.

Links:

Running JavaScript in Rust with Deno.

If you don’t have Rust installed yet you can use the rustup installer. ↩︎
We neglect the cleanup step. To safely dispose of the V8 engine and platform add following code at the end of the script:
```
unsafe {
    v8::V8::dispose();
}
v8::V8::dispose_platform();
```
You will need to wrap the code related to the Isolate in a local context to avoid segmentation fault when disposing of the platform with an Isolate still being within the context. ↩︎
While most services follow the WHATWG and W3C specifications for JavaScript runtime APIs there’s larger standardization effort led by WinterCG - Web-interoperable Runtimes Community Group. ↩︎
CloudFlare Workers Runtime APIs ↩︎

February

matousdzivjak@gmail.com (Matouš Dzivjak) — Wed, 01 Mar 2023 00:00:00 +0000

Back to reading, writing, and living.

On 6th at 23:00 our final leg of the inbound flight from Tenerife finally landed in Prague. After almost 5 weeks we returned to the grey reality of mainland Europe, sub-zero temperatures, and windy weather. I welcomed the return. The long workation made me realize that there’s certain beauty to the mundanity of regular workdays and daily routines.

I din’t stay long in Berlin and on Friday we already went backcountry skiing in Krkonoše. Reminder for future self - trying out shoes or skiing boots at home doesn’t imply the same comfort on the slops, or when hiking or running. A lesson I learned 10 times and forgot 10 out of them.

One of the weekends we visited Fine Bagels with Ena. The place reassured me of what I thought for a long time - books are the best type of decor for any space. Furthermore, I am becoming devotee of bagels as a breakfast meal. The only contender being Kimchi Cheese Waffle that I had a day after during a brunch at ABC - Allans Breakfast Club. We might be back from Spain but the coffees and bagels are to stay (at least so I hope).

Right now I am writing from Spain again, this time Mallorca.

Reading

I am finally back in the reading game, thanks in part to spending more time around friends that read a lot (and fast, which I envy greatly). I am ending February with 3 books on the scoreboard; Staff Engineer by Will Larson, No Rules Rules by Reed Hastings and Erin Meyer, and High Output Management by Andrew S. Grove.

Now I am half way through another gem, Stranger in a Strange Land, and I am finding the long lost delight for novels. And not just reading novels, but enjoying time by reading books that bring emotional joy and are not another mean to feel productive.

TWH#45: Against Overwhelm
- Become intentional with how you spend your time and energy.
- Clarify what are your goals and how they align with your company and team so you have a framework for how not to spend your time.
- Focus on leverage instead of productivity. E.g. what are the multipliers of your work?
- Focus on one thing and one things only.
Your DietBet Destroyed the World (fiction)
The End of Writing perfectly sarcastic take on ChatGPT
Worship

The Great People Shortage is coming — and it’s going to cause global economic chaos outlines the grim future due to population decline and the falling ratio of working to retired people. We will have to focus on productivity and automation to keep the income high enough to support the retired population. Higher productivity and utilization requires faster requalification for displaced workers and better education for upcoming generations. One is left to wonder how that will turn out with teacher salaries being as low as they are.

The other option is to expand the workforce via immigration. Something certain countries still seem to be reluctant to do (wink, wink Czech republic). Furthermore, we will need to get better at supporting immigrants (language and relocation support, qualification) if we expect people from other cultures to integrate well within the countries.

Last but not least, one is left to wonder how this will turn out for retired people. Will we be able to support the ever-growing old population? Will the government be able to fullfill their needs? And even if, will we have enough people to take care of them? My parents might have set themselves up well with 4 children after all…

This month I learned

I am digesting a few learnings from the newly read books. One of the large takeaways is the importance of leverage. As you progress through your career, regardless of the path or industry, your job shifts from contributing to providing contribution leverage for other members of your team.

In Software Engineering being the empowering factor can mean many things: setting culture, leading by example, writing RFCs, creating well-written tickets for others to work on, doing knowledge-sharing sessions, and more. The point being, you need to learn to value the output of your team (and the whole organization) more than yours (in terms of individual contribution) on your way up the career ladder.

Anthropomorphism is the attribution of human traits, emotions, or intentions to non-human entities. It is considered to be an innate tendency of human psychology.
Hedonic treadmill is human tendency to quickly return to relatively stable level of happiness despite major positive or negative events.

Watching

Suits rewatching when training indoor on the bike.
The Last of Us. Never played the game but saw a few gameplays and loved it. Compared to Uncharted the execution is brilliant and I really enjoyed all episodes so far. Let’s hope this starts a trend of faithful game adaptations.

Listening

Stranger in a Strange Land

matousdzivjak@gmail.com (Matouš Dzivjak) — Wed, 01 Mar 2023 00:00:00 +0000

TODO

High Output Management

matousdzivjak@gmail.com (Matouš Dzivjak) — Fri, 24 Feb 2023 00:00:00 +0000

Notes

Grove’s Principle of Didactic Management - “Ask one more question”
- when you think the other party has said everything ask one more question
- keep the flow by asking more until both parties feel satisfied
productivity can be increased by performing work at higher rate or by increasing the leverage of activities (e.g. by work simplification)
manager’s output = team output + output of neighbouring teams under their influence
manager’s job is to strive for the highest leverage
high leverage activities:
1. when many people are affected by one manager
2. when a person’s activity or behaviour over a long time is affected by manager’s input
3. when a large group’s work is affected by an individual supplying key piece of knowledge or information
big part of managers role is information gathering
delegation is another way of applying leverage
training others

Production operations

process - building a software
assembly - the software itself
test - assessing the quality of the software

Meetings

process oriented (scheduled on regular basis)
- 1:1
  - purpose: mutual teaching and exchange of information
  - should be scheduled in frequency matching the job- or task-relevant maturity (e.g. more frequently with new team member)
  - agenda and tone should be set by the subordinate
  - emphasis should be on indicators that signal trouble
  - keep a file with notes for next meeting and action points from previous
- staff meeting
  - between manager and the peers of the team
  - manager should be active only if the discussion is stalling or going off track
mission-oriented meetings
- held ad-hoc to address specific issues
- the objective of the meeting must be clear
- keep the meetings reasonable sized, decision-making is not a spectator sport
- meeting should have a driver
  - responsible for preparing the meeting, keeping discipline during the meeting, and summarising it afterwards
- shouldn’t consist more than 20% of the meetings, in smoothly running organisation all issues would be addressed before they arise in process oriented meetings

Decision making

the process:
1. free discussion
- all aspects of the issue should be openly and freely discussed
1. clear decision
2. full support
- all involved parties should commit to the decision (doesn’t mean agree)
if solution is wrong, repeat the steps
the decision should be made on the middle level between reliance on technical knowledge and hands-on experience versus expertise and previous experience with similar solutions
six important questions for decisions making:
1. what decision needs to be made
2. when does it have to be made
3. who will decide
4. who will need to be consulted prior to making the decision
5. who will ratify or veto the decision
6. who will need to be informed of the decision
being clear about the decision making process beforehand is important to prevent hard feelings

Planning

establish projected need or demand

examine your environment: customers’ expectations, performance of other groups that affect you, competition.
examine the environment in two timeframes: now vs. sometime in the future (e.g. in 1 year)
difference analysis - the environment demands now vs. in the future
- how you react to the difference is key outcome of the planning process

establish your current status

current capabilities and projects and their delivery

compare and reconcile steps 1. and 2.

what do you need to close the gap?
what can you do to close the gap?
consider both questions separately and answer: what affect your actions will have and when
the set of actions you decide on is strategy
management by objectives (MBO)
- answer to two questions
  1. where do I want to go? (objective)
  2. how will I evaluate if I am getting there? (key result)

Behaviour

when person is not doing their job there are only two possible reasons: they can’t do it or they won’t do it
- manager can affect this by motivation and training
Maslow hierarchy of needs:
1. Physiological (things that money can buy such as food or clothing)
2. Safety/Security (e.g. medical insurance)
3. Social/Affiliation (e.g. belonging to the group)
4. Esteem/Recognition (exists in the eyes of the beholder, e.g. you dictate what you need for esteem/recognition, once gratified it no longer motivates)
5. Self-Actualizaton (the need to achieve one’s utter personal best)
competence-driven - driven to master specific task
achievement-driven - attempting to achieve no matter what the task is
motivation by money dimishes with higher income
the motivation persists for those who have money as proxy for achievement
- if absolute sum is important to the person then it is mostly about physiological need
- if what matters is how the sum stacks against other peers then it is mostly about esteem/recognition or self-actualization

task-relevant maturity (TRM)

combination of education, training, and experience
can be high in one job and low in another
management style for specific maturity:
- low - structured; task oriented; what, when, how
- medium - individual oriented; mutual reasoning and communication
- high - minimal involvement of the manager

Reviews & feedback

assessing performance
- clarify for yourself in advance the expectations
- you can characterize performance by output measures (the yield) and internal measures (the means to achieve the yield)
- needs to weight in if the person is long-term oriented vs short-term oriented (no general rule here)
- similarly there might be lag between actions and actual results
delivering the assessment
- 3 Ls:
  - level - level yourself with the person and be frank
  - listen - what matters is getting the right thoughts communicated, words are just the means for it
  - leave yourself out - the review is about and for the person
- there’s finite capacity to absorbing feedback
  - write down things and group similar feedback
stages of under-performers: ignore, deny, blame others, assume responsibility, find solution
- three possible outcomes when delivering “blast” review (harsh feedback)
  - they accept the assessment and commit to solution
  - they don’t accept the assessment but still commit to solution
  - they neither accept the assessment nor the solution
reviewing the ace
- high performers need strong feedback even more than average performers as they account for disproportional amount of work

Compensation and career

career progression consists of alternating between meets requirements and exceeds requirements until one stagnates at meets requirements
people are fine with meeting requirements while achiever strive for exceeding requirements
when person is promoted and becomes under-achiever it’s better for both the organisation and the person to adjust their position
- the management oughts to own to the error

Practice

Tasks from the end of the book to practice what one has learned

for a project you are working on, identify limiting step and map the flow of work around it
identify 6 indicators for your group’s output, they should measure both quality and quantity
conduct work simplification on your most tedious, time-consuming task
define output of your organiszation and organizations that you can influence
define how you will monitor the next project that you delegate
define 3 objectives for yourself and create key indicators for all of them

No Rules Rules

matousdzivjak@gmail.com (Matouš Dzivjak) — Sun, 19 Feb 2023 00:00:00 +0000

Notes

Certain points are too capitalistic even to my liking.
For most companies many of the learnings are out of reach, for example paying top of the market and hiring rock star employees.
Candor is the most important part that can be applied even if you can’t pay top of the market.
Removing controls (in decision making and expenses) leads to innovative and faster-moving organization.

Giving feedback

Aim to Assist: feedback must be given with positive intent
Actionable: feedback must be actionable and focus on what the recipient can do differently
Appreciate: when receiving negative feedback avoid the natural instinct to be protective and show appreciation instead
Accept or Discard: the decision to react is entirely up to the recipient

Step one

Built talent density
- Talented people make one another more effective.
- Averagely performing people can drag the performance of high performing team members down.
- Inversely, performance is contagious.
Increase candor
- Say what you really think with positive intent.
- Teach all employees to give and receive feedback well.
- Build feedback into your regular meetings.
Begin removing controls
- Remove vacation policy, but the leaders have to set example by taking time off themselves.
  - The boss should provide a context for the team of when and how to take the vacation.
- Remove travel and expense approvals, but ensure that employees follow spend company money as if it were your own.
  - The finance department should audit portion of receipts annually>
  - Speak about abusing the system openly so others understand the ramifications of behaving irresponsibly.
  - Some expenses might increase but not nearly as much as the gains from the freedom that they provide.
  - Fewer resources waster on administrative cost.

Step two

Fortify talent density
- Divide workforce into creative and operational employees, pay creative employees top of the market salary.
- Don’t pay performance based bonuses, put the resources into salary instead. Measures for performance based bonuses are often wrong and don’t reflect long-term incentives of the company.
Pump up candor
- Instigate culture of transparency, get rid of closed offices.
- Open up the books to your employees and share sensitive financial and strategic information with everyone.
- When doing layoffs or other decisions that will impact employees’ well-being be up front to build trust (might cause anxiety and distraction).
- As long as you’ve already shown yourself to be competent speaking about mistakes will increase trust, goodwill, and innovation.
Remove more controls
- Don’t seek to please your boss. Seek to do what is best for the company.
- In fast and innovative company, ownership of critical decisions should be dispersed across the workforce at all levels.
- Teach employees to take risks but if they fail, to sunshine it openly

Step three

Max up talent density
- The Keeper Test
  
  If a person on your team were to quit tomorrow, would you try to change their mind? Or would you accept their resignation, perhaps with a little relief? If the latter, you should give them a severance package now, and look for a star, someone you would fight to keep.
- Skip PIP (Performance Improvement Plan), rather take all the money and give it to the employee in a form of severance payment.
- Encourage employees to use the Keeper Test Prompt with their managers.
- When employee is let go, speak openly about what happened.
Max up candor
- Don’t link 360 feedback to raises or promotions and avoid anonymity.
- Open comments to anyone who is ready to give them.
- Start, Stop, Continue method with 25 percent positive, 75 percent developmental - all actionable and no fluff.
Eliminate most control
- Lead with context, no control. Your goal needs to be innovation (not error prevention) and you need to be operating in a loosely coupled system.
- Don’t tell people what to do, get in lockstep alignment by providing and debating all the context that will allow them to make good decisions.
- When something doesn’t work out, ask yourself what context you failed to set.
- Loosely coupled organization should be a tree, not a pyramid. The boss is the root, holding up trunks - senior managers who support the outer branches where decisions are made.
- If team is moving in the desired direction using the information they’ve received from you and others around you know that you’re successfully leading with context.

Show, don't tell

matousdzivjak@gmail.com (Matouš Dzivjak) — Sat, 11 Feb 2023 00:00:00 +0000

Show, don’t tell is a writting technique that allows the reader to experience and relate to the story through actions and feelings rather than exposition. The show, don’t tell rule applies to all kinds of written text from poetry to screenwriting. Can the rule be extended to engineering documents as well?

Presentations are the first place where the Show, don’t tell rule works well. Nothing gets the audience bored more than a wall of text on every slide. In the case of presentations show, don’t tell applies to both the content of slides and the presenters speach. Tell or show the listeners the story (e.g. “Our users are having issues using our product in such and such way”) and let them figure out the rest. Here’s a wonderful example from my colleague Johanneses recent presentation for the Incident of the month.

Another place where the Show, don’t tell rule can help you is in RFCs and architecture documents. Explaining relationships, models, flows, or service dependencies is hard and often neglected by the person writing the document because they might already have the necessary context to build the mental model. The easier way to get everyone on the same page is to provide visual guidence. Here’s an example from our RFC on the introduction of External Authorization API showing the flow between an user and our services.

Following the Show, don’t tell rule requires more effort but there are several benefits to it:

Most people are visual learners and can extract information better from images than walls of text.¹
Drawing or mapping down problems and solutions helps also you - the author - align your thoughts.
Visual explanation often reduces the ambiguity of written text.

In short, tell the audience the story or issue and let them draw conclusions from there without forcing your narrative. This brings wider range of opinions into discussion and makes the others more interested. And when applicable, provide visual material alongside the text to help the readers understand the models or flows so that you can focus on the important things instead of explaining ambiguities in your writing.

https://papers.ssrn.com/sol3/papers.cfm?abstract_id=587201 ↩︎

Staff Engineer

matousdzivjak@gmail.com (Matouš Dzivjak) — Sat, 11 Feb 2023 00:00:00 +0000

Staff Engineer is a concise look at leadership beyond the management track. The book was written by Will Larson who worked at companies such as Stripe or Uber. In around 150 pages he summarizes his view on Staff+ engineering and the other half of the book contains interviews with engineers from other companies. While subjective, many of the points in the book seem to be the general consensus in the industry on what Staff+ engineering should look like. Some chapters contain more substance (e.g. Work on What Matter) while others seemed to me like re-iteration of what I would expect from engineers on any other level or even just decent human beings (Get in the Room and Stay There in particular contains a few points that read to me as don’t be an duchebag).

Notes

When advancing through the career ladder the timeframe of initiatives get longer from weeks (sprints) to months or even years.
Shift from decision making and executing towards giving space to others and steering them in the right direction.
A lot of it is about networking and being friends with the right people or being in the right place at the right time.
Enging chapter also includes a few tips for managing and hiring staff engineers.

Archetypes

Tech Lead

carry team context
closely cooperate with product manager
build agreements inside team

Architect

focus on specific technical domain (e.g. API design)

Solver

move around to solve specific burning issues

Responsibilities

setting technical direction - advocate for technology and how it applies to the specific problems of the company
mentorship and sponsorship - sharing experience and advice while understanding the recipients domain.¹
providing engineering perspective - be invited into meetings to inject engineering context for critical decisions
exploration - research topics, build proof of concepts, build generic understanding of topic to make informed decision
being glue - doing the needed but invisible work²

Operating at staff

work on what matters
- avoid snacking - working on low effort low impact things when you run out of low effort high impact initiatives
- avoid preening - working on low effort high visibility work
- existential issues - the first place to look for work is exploring whether the company is experiencing an existential risk
- work where there’s room and attention - work on things that will become critical in the future
- foster growth - dedicate time to grow the team around you
- edit - once you have the context you might be able to contribute small changes that actually push existing project by a lot
- finish things - help where things are not getting buy in (and should) or when they need to be taken over the finish line
engineering strategy³
- why? allows teams to move quickly and with confidence, e.g. the team doesn’t need to do week of research on database storage because the chosen few that are used in the company are already part of the engineering strategy
managing technical quality
- fix hot spots causing immediate problems
- adopt best practices that are known to improve quality
- prioritize leverage points that preserve quality as the software grows, e.g. good data model, well defined API, etc.
- align on techical vectors - the initiatives in the team and accross team should lead to shared goal
  - give feedback, encapsulate your approach in workflow and tooling
- do fewer things but do them better
listening through questions, i.e. asking good questions that open further discussion, the question has to be well intended with the purpose of learning more and the other party must feel safe to answer it
discussions
- shift your contribution towards asking questions
- pull people that aren’t participating into the discussion
- take notes (duh)
decisions
- write down the problem, think hard, write down the solution framework
- circulate early, i.e. get input early in the decision-making process
- separate style from substance, i.e. stop giving style feedback because everyone has different writing style and idea of the document structure. Instead, focus on the substance.
- be open to changing your mind
presenting to executives
- situation: the context of the problem
- complication: why is the current situation bad
- question: what is the core question to answer?
- answer: what is your best solution/answer to the posed question?

2022 Review

matousdzivjak@gmail.com (Matouš Dzivjak) — Sat, 04 Feb 2023 00:00:00 +0000

2022 was a ride. Literally and methaphorically. I spent time running, skiing, cycling, went as a best man to my friends wedding, raced a few races, got to know better bunch of wonderful people from Berlin and much more. It was an intensive year, not sportwise (here I actually did worse than last year; more on that later), but emotionally and personal-growth-wise.

To quickly recap the events of 2022: I went skiing to Austria in January and again in February, cycling in Mallorca in March. On April 4th I went as the best man to my friend - Dominik’s wedding. I did a terrible job as the best man. Instead of planning and attending the bachelors party I was cycling in Spain and my only contribution was a little manual help the day before, mediocre speach before the dinner, and moderating part of the evening fun. I just hope that Dominik knows me well enough at this point that he didn’t expect otherwise. Either way, it was fun, nice, modest, and sweet.

Week after the wedding we had a primary school reunion after 10 (ten) years. I saw a bunch of familiar faces that we keep in touch with on semi-regular basis and bunch of people I haven’t seen for 10 years. It was ammusing. In high school the collective seems already filtered to specific social bubble but that same doesn’t hold true for primary school. Part of the old schoolmates already have children and families while other are still alone (me?). Most of the evening revolved around small talk and catching up on insignificant life events. What stood out the most to me though is that everyone is still mostly the same, from looks to behaviour.

In May we have spent a week in Portugal on a SumUp Hack Week. Our project was called SumUp for Developers and the objective was to improve our developers website which, thanks to the capable and self-driven people that joined the team, ended with a solid success (albeit not a winning project). The event included 400 people from the company yet I’ve spent most of the time with Stepan, Ena, and Julien occasionally interacting with other people that I know mostly by their Slack handles. Getting better at small talk and bonding might be helpful before the next week (who am I kidding, I enjoy my small group of friends and have long given up on trying to change that).

Before flying to Portugal I also did my first Marathon after 2 years. I finished in 2:59:50 as the last person before the 3 hour mark. Last 5k my quads were cramping and I had to walk a few times which I attribute mostly to the heat and poor aid stations (sorry, clear suger and salt doesn’t really cut it for me on a paid event). The only saviour was Dominik who came to support me and passed me a few gels and a water along the road.

Beginning of June, two weeks after coming back from Portugal, I participated in Labe Run race. A race that tracks the Czech part of river of Labe in it’s (almost) full length - 380 km. The race if raced in 6 - 12 member teams, each person running 3 to 4 segments around 10km long, and usually takes around one a half day to complete. Our team Mlč a Šoupej Nohama ended in a beautiful 9th place out of 79 teams in 31:34:00. For me the biggest win and a proud moment was having the 2nd, 4th, 5th, and 1st fastest times on by segments respectively. (thank you Verča for introducing me to this fun side of running that makes it feel like a team sport)

In June we went to Austria for a cycling camp with Ondra, Jakub, and David. Apart a few hilly rides we rode the Glossglockner High Alpine Road up to Kaiser-Franz-Josefs-Höhe and did a crazy fast descent swerving between tens of firetrucks that just on that day attempted (and succeeded in doing so) the world record for pumping the water 1430m up. From the valley to the Edelweißspitze. At the end of the trip I also did my first aero bike ride, just week before my first Ironman.

On 25th June I completed Ironman Hamburg in excruciating 11:34:42. Heat and high-output activities simply don’t work well for me and on the day of the race the temperatures reached above 30°C. I executed solid swim (to my capabilities), went a little bit too hard on the bike and knew that I am in for a treat already 60km before starting the run. On a run I discovered 2 things. One - there’s reason there are dedicated cycling shoes for triathlon. After taking my regular carbon-sole and super stiff road bike shoes off I simply couldn’t run (which luckily got better over first few kilometers). And second - once your body core temperature gets over the threshold, there’s no going back. I ended up running and mostly walking a 4:39:04 marathon, puking a few times, but at least I tested my mental resilience before the ultratrail races that I had coming later that year.

After Ironman Hamburg I went to Berlin to spend a week working from the office after which, in early July, we flew with my parents to Spain where I had my first ultratrail race. Ultratrail Val d’Aran Pyrenees by UTMB, specifically the CDH (second longest) version, is a 105km long race with 6100m of elevation. The detailed report is in the July journal entry but in short, I didn’t finish. This time mostly due to simply not being ready and in part also to again spending most of the race in a heat far above my tolerance zone.

Sports

In progress…

Finances

In 2022 I stopped tracking my finance in ledger. One reason being it taking a lot of time. The other being that tracking all of my spending for 2 years gave me a good idea of where I am spending the most - sports and rent.

This year I was definitely spending more on eating out, drinks, travel, and generaly on myself. I also saved less than the year before which I feel bad about and intend to fix this year. In 2021 I managed to put 18.469 € aside compared to 11.000 € this year. I attribute this in part to higher expediture and in part to overall downturn of the financial market which makes made me realise that even index traded funds are not as save of an investement as I though they are. On the other hand, I have built substantial cash reserve and hope to expand it further to 3 months worth of salary of unexpected expenses.

2023

In progress…

If you endured up to this point - thank you, I wish you a lovely year.

January

matousdzivjak@gmail.com (Matouš Dzivjak) — Wed, 01 Feb 2023 00:00:00 +0000

We’ve spent the whole of January in Tenerife with group of great friends (people) from the office. The coffee and pastries consumption was through the roof and apart from work we managed to squeeze in a lot of fun as well: night hike to Teide, paragliding, surfing, and plenty of dinners, walks, and deep talks. In short, I had fun, felt happy, and enjoyed the company. 32 days was admittedly a lot and the productivity was on decline in last 2 weeks so one consideration for next iteration of the Winter Berlin Escape would be to make it shorted or take more days of full time off.

＊

This month Hashicorp released their RFC management tool called Hermes and we had a long discussion about the absence of a proper RFC process at SumUp. In my opinion this hinders cross-team collaboration, undermines enforceability of company-wide standards, and makes it hard for non-senior engineers to raise issues to higher ranks. The dream would be to have something like Oxide’s RFD 1 and a management system that would consolidate RFCs from all tools that we use right now (Confluence, Google Docs, GitHub) into single tool that would make it easier to discover, follow, and reference RFCs.¹

Reading

Mike Acton’s Expectations of Professional Software Engineers.
Iteration isn’t just for code: here are our latest API docs. Yet another reminder of how poor are we doing public APIs at SumUp.
A Boat Fire Killed 34 People, and We May Never Know Why
Why are you so busy? - you should ever be so busy only on purpose.
It Hurts to Ask

We analyze the offering, asking, and granting of help or other benefits as a three-stage game with bilateral private information between a person in need of help and a potential help-giver. Asking entails the risk of rejection, which can be painful: since unawareness of the need can no longer be an excuse, a refusal reveals that the person in need, or the relationship, is not valued very much. We show that a failure to ask can occur even when most helpers would help if told about the need, and that even though a greater need makes help both more valuable and more likely to be granted, it can reduce the propensity to ask. Furthermore, when potential helpers concerned about the recipient’s ask-shyness can make spontaneous offers, this can turn out to be a double-edged sword: offering reveals a more caring type and helps solve the failure-to-ask problem, but not offering reveals a not-so-caring one, and this itself deters asking. This discouragement effect can also generate a trap where those in need wait for an offer, while potential helpers wait for an ask, resulting in significant inefficiencies.
The Great People Shortage is coming — and it’s going to cause global economic chaos

This month I learned

Preparedness Paradox - The preparedness paradox is the proposition that if a society or individual acts effectively to mitigate a potential disaster such as a pandemic, natural disaster or other catastrophe so that it causes less harm, the avoided danger will be perceived as having been much less serious because of the limited damage actually caused. The paradox is the incorrect perception that there had been no need for careful preparation as there was little harm, although in reality the limitation of the harm was due to preparation. Several cognitive biases can consequently hamper proper preparation for future risks.

Watching

Walmsley Part 3 Presented by Wahoo + HOKA - Jim Walmsleys 4th place on UTMB
Suits rewatch in late evenings.

Listening

There’s a lot left to be desired: https://github.com/oxidecomputer/cio ↩︎

Training for the Uphill Athlete

matousdzivjak@gmail.com (Matouš Dzivjak) — Tue, 24 Jan 2023 00:00:00 +0000

Training for the Uphill Athlete is book focusing on the endurance athlete physiology and training written by the biggest names in the field. First chapter breaks down the important scientific concepts behind sporting such as aerobic capacity, VO2max, and heart rate zones. Chapter two talks about the methodological basis of endurance from training volume, to testing and recovery. Chapter three is about strength training that is important part of race preparation even for endurance athletes. And in the last - fourth section - one can find examples of training plans for different parts of the season and generic tips for structuring yours plan as there’s no one-size-fits-all.

Notes

As with all other sources: focus on the base, 80% of training should be in Zone 1-2.
Strength training is meaningful (a lot) even for endurance athletes.
4 week blocks with 3 weeks of intensity and one recovery work well.
There are great recommendations for training plans in the book that wouldn’t fit here.

December

matousdzivjak@gmail.com (Matouš Dzivjak) — Sun, 01 Jan 2023 00:00:00 +0000

Reading

Drowning in AI Generated Garbage : the silent war we are fighting

The algorithms are already feeding themselves on their own data. And, as any graduate student will tell you, training on your own results is usually a bad idea. You end sooner or later with pure overfitted inbred garbage. Eating your own shit is never healthy in the long run.

This month I learned

Longtermism is a philosophical position that focuses on the long-term consequences of actions and policies. It is a way of thinking that prioritizes the future over the present, and it often involves considering the potential impact of decisions and actions on future generations. Longtermists believe that it is important to consider the long-term consequences of our actions and make decisions that will have the greatest positive impact over the long term. This can involve prioritizing investments and policies that have the potential to bring about long-term benefits, even if they may not provide immediate or short-term gains.

Listening

Watching

Dave Not Coming Back is a documentary about Dave Shaw’s death while retrieving a Deon Dreyer’s body from 240m under water. I already read about the incident a few years ago in a long form artile titled Raising the Dead which is so well written that it felt like I am watching the documentary for a second time. I highly recommend both (or either), it’s a story about passion, courage, grief, and limits of the human body.

November

matousdzivjak@gmail.com (Matouš Dzivjak) — Thu, 01 Dec 2022 00:00:00 +0000

We are on a cycling trip to Dénia number 2. This time I am doing proper recovery days to avoid returing with a crash syndrome again. Walking downstairs backwards wasn’t a lot of fun.

Reading

I finally finished The Art of Thinking Clearly that I got from Ena back in August. This year I am embarrassingly slow with the books. Other than that I had some time for long form articles and several forgotten blog posts among the 120 open Safari tabs on my iPhone.

So long and thanks for all the bits
Reminiscing: the retreat to comforting work. - on how we snack on easy tasks while avoiding the complicated.
Ask HN: How do I find my “purpose”?
Ask HN: Advice that changed your life?
A Boat Fire Killed 34 People, and We May Never Know Why - a thrilling long form article about a fire on a diving live deck boat.

This month I learned

Horses for courses - used to say that it is important to choose suitable people (or items) for particular activities because everyone has different skills¹.

A smart accountant once told me that the answer to “How much money did you make?” is always, “Who wants to know?” If it’s an investor, the answer is “A lot.” If it’s a customer, the answer is “A little.” If it’s the IRS, the answer is “None.” edw519

Listening

https://dictionary.cambridge.org/dictionary/english/horses-for-courses ↩︎

The Art of Thinking Clearly

matousdzivjak@gmail.com (Matouš Dzivjak) — Mon, 28 Nov 2022 00:00:00 +0000

The Art of Thinking Clearly is a book that provides practical tips for improving one’s thinking and decision-making. The book covers a wide range of topics related to cognitive biases, logical fallacies, and other common pitfalls of human reasoning. In many ways it overlaps or references Thinking, Fast and Slow by Daniel Kahneman.

Throughout the book, Dobelli uses real-world examples to illustrate the various cognitive biases and logical fallacies that can affect our thinking, and provides practical advice on how to avoid these pitfalls. He also discusses the importance of critical thinking and the need to question our assumptions, as well as the benefits of adopting a more logical and analytical approach to decision-making.

The Art of Thinking Clearly is a highly accessible and engaging book that offers valuable insights into the human mind and how it can be improved. It is a useful resource for anyone looking to improve their critical thinking skills and avoid common mistakes in reasoning.

Thank you Ena.

October

matousdzivjak@gmail.com (Matouš Dzivjak) — Sun, 06 Nov 2022 00:00:00 +0000

Reading

Why I built a dictionary app - designing dictionary app from ground up.
How I regained concentration and focus
Productivity Porn

Productivity porn is anything that after having been consumed makes you feel like you were productive when in reality you didn’t actually do anything.

I.e. saying “I learned something new” after 30mins of reading Hacker News is productivity porn. The key is that you benefit from doing the actual activity, but not from thinking about doing it.
Your DietBet Destroyed the World - fictional story about the world ends in an unusual twist.

This month I learned

Effective altruism is a philosophical and social movement that advocates “using evidence and reason to figure out how to benefit others as much as possible, and taking action on that basis”. People who pursue the goals of effective altruism often choose careers based on the amount of good that the career achieves while donating to charities based on maximising impact.¹

Listening

https://www.effectivealtruism.org/ ↩︎

September

matousdzivjak@gmail.com (Matouš Dzivjak) — Sat, 01 Oct 2022 00:00:00 +0000

Reading

Why are you so busy?

You and your team should never be so busy that you can’t do your job properly or that you begin to hate your work. Especially if you’re a leader or a leader-of-leaders, then you should actually (yes you should, I’ll die on this hill) have free time to think alone, and to talk and ideate organically with peers. Contrary to popular belief: back-to-back meetings isn’t a badge of honour, it’s a red flag.

The Maintenance Race

The world’s first round-the-world solo yacht race was a thrilling and, for some, deadly contest. How its participants maintained their vessels can help us understand just how fundamental maintenance is.

Wonderful long-form article about 3 sailors that attempted the Sunday Times Golden Globe Race in 1968 and their different approaches to the race.

From the article:

Knox-Johnston’s style was: “Whatever comes, deal with it.” And he did.
Crowhurst’s was: “Hope for the best.” It killed him.
Moitessier’s was: “Prepare for the worst.” It freed him.

Knox-Johnston was the best prepared one, he brought all possible equipment and spare parts he might need for the voyage and spent countless hours maintaining his ship. Crowhurst hoped for the best and was unprepared, not long into the race he started lying about the progress and when it was finally certain and it all will come into the light, he committed suicide. Moitessier’s approach was based on minimalism and low-maintenance, he stripped his yach of all things unnecessary, he didn’t user any electronic equipment (he passed his messages to by-passing boats via a slingshot), and his ship was made out of steel.

The race has its third edition this year (2022 Golden Globe Race) which started on 4 September 2022. The race honors the first edition by imposing rules to limit the equipment and yachts to what was available to Sir Robin Knox-Johnston in 1968. Raced yachts must comply to for example following rules:

Constructed of fibre reinforced plastic.
Designed prior to 1988, with a minimum series of 20 yachts built from one mould.
Has a hull length of between 32 to 36 feet (9.8 to 11.0 m). Bowsprits, wind vanes and outboard rudders, boomkins, pushpits and pulpits are not measured.

This month I learned

The IKEA Effect - Why people fall in love with their own ideas - people overvalue things in which they put effort into (both objects and ideas). The effect greatly contributes to two more pitfalls: sunk cost fellacy and “not ivented here” syndrome. The ways to avoid The IKEA Effect:
- Acknowledge your unconscious bias.
- Spike rough prototypes to test ideas early.
- Talk to customers (listen to customer struggles instead of selling your solution).
- Run growth experiments - setup problem statement, hypothesis, and success criteria upfront to avoid confirmation bias.
“Not ivented here” syndrome - tendency to avoid buying products, services, or knowledge from external sources.

Listening

August

matousdzivjak@gmail.com (Matouš Dzivjak) — Thu, 01 Sep 2022 00:00:00 +0000

First week of August we spent in Portugal with the family close to Nazare, the pinnacle of surfing. A nice whole-family vacation in a long time and I am glad for the time we were able to spent together.

Not much more intesresting sutff this month except maybe SumUp’s Summer party that was a lot of fun and I’ve got the chance to meet a lot of people physically after spending quite some time with them in the Zoom calls. I also got introduced to the proper way of brunching. To my best knowledge, proper brunch starts the day before when you need to acquire hangover and ensure that you get only a few hours of sleep in order for the brunch to hit just right. The brunch itself must begin no earlier than at 12am, has to include at least one alcoholic beverage, coffee, and meal (anything more than 1 is welcomed but not mandatory). The conclusion is, I am definitely more of a brunch person than lunch or dinner person. If you manage to do an activity before, your daily dose of happinnes can be basically fullfilled by around 2 hours into the brunch and you have the rest of the day to not do anything.

If the sun’s out and you have another day on this Earth, what’s there to be worried about? Alyssa Limperis

Reading

Looking back at two years at Automattic and Tumblr
On owning a software problem - list of low-friction small thing that most people will not notice, but that when they do, it’s a sign of craftsmanship, expertise, and pride in your work. Notably:
- Accurate documentation of a repo and an easy, reproducible way to run the project
- Formatted and linted SQL statements
- Editing typos and inaccuracies in old communications
- Explaining acronyms and industry jargon when in an audience that might not be familiar with it, and being cognizant of when they’re in that audience
But there’s no dispute that everyone will find their own. For me this would for example be leaving comments
Gardening Platforms - about software platform teams.
The Case for Bad Coffee - Essay not about coffe, but about people and experiences in live being more important about product. It’s about a product’s quality being defined not by its substance but by its reminder of things that can’t be purchased.

Bad coffee is the stuff you make a full pot of on the weekends just in case some friends stop by. It’s what you sip when you’re alone at the mechanic’s shop getting your oil change, thinking about where your life has taken you; what you nurse as you wait for a loved one to get through a tough surgery. It’s the Sanka you share with an elderly great aunt while listening to her tell stories you’ve heard a thousand times before. Bad coffee is there for you. It is bottomless. It is perfect.

This month I learned

Chesterton’s fence - The principle that reforms should not be made until the reasoning behind the existing state of affairs is understood.

Listening

July

matousdzivjak@gmail.com (Matouš Dzivjak) — Mon, 01 Aug 2022 00:00:00 +0000

On the 8th of July I attempted my first ultra race - Ultratrail Val d’Aran by UTMB. The race took a place in Spain Pyrenees and was my first encounter with this part of Europe. I didn’t train much for the race and to make the matter worse I franticly decided to catch up with the training and aclimatise the week before the race. Leading into the race I did 2 long runs on Monday and Tuesday followed by 2 very easy days before the race.

I woke up at 4:15 and had a light breakfast consisting of granola, oat milk, blueberries, and skyr-style soy yogurt. The race started early in the Morning at 6pm with a packed field. Contrary to what I was told to do I started fast and tried to get to the front of the field (I started at the very end). This meant overtaking a few hundred of people over the course of first 25km until the field finally thinned out.

After the first quarter I felt confident. The legs were feeling good, we already had large chunk of the vertical meter behind us and I was able to consume calories at a reasonable rate. The good spirit continued up to 45th kilometer to the first aid station with support allowed.

Instead of taking my time (which I should have done and will definitely do next time) I rushed through the aid station leaving in less than 10 minutes after chuging down 2 cups of cola, 1 cup of soup, handful of raspberries and blueberries, but nothing of substance. At this point it was already 13pm and I was slowly heating up in the blistering heat.

The aid station was followed by 1600m vertical descent that hurt a lot. My quads are not used to the pounding so by the end I was praying for the next climb. At this point I started to feel sick, my legs were heavy, head disy, and I was having trouble cooling down.

Most of the time between the descent and the next aid station on 62th km I spent walking. At the aid station I lied down for a bit as my head was spinning. For a moment I was considering giving up and it took me 20 minutes to regain some composure, drink a few cups of cola and water, and set off.

The following 14 km segment was the worst running experience I ever had (yet). My stomach was upside down and I was seeking every opportunity to wash my face and soak the cap in the cold water running down the hill. I walked, and walked, and then walked some more. The 14km between the two aid stations took me 3 hours and by the end even walking hurt.

I ended the race on 76th km, 29km and 2000m vertical before the finish line.

＊

This month we did some cycling at Cihelny close to Karlovy Vary with the dentist group. It was fun and hilly ride with Klínovec being the highest point. The day after we went for an easy trail run instead early in the morning with Verča. Nothing groubreaking.

More interesting was the last weekend, on 30th August Breadfit store Litoměřice organised the 4th annual Einstuck ride titled Transcendence. I knew only Lukáš, the owner of Breadfit store and Vojta, who joined for the ride, until that point. The rest of the peloton (which was around 30 head strong) were all interesting invidiuals (read hipsters) from Prague up to Bratislava.

The ride we did was long and rainy. It started very hard with a few short 360w+ efforts up the small hills close to Litoměřice when I tried to keep up with Feňdák. I gave up not short after and decided to keep up more reasonable tempo with the group behind. We stopped two times, one time for lunch and the other for a really bad coffee at which point it was already 4:30pm and we still had more than 120km to go so we ended up splitting from the group only with Vojta a went full TT mode from Bad Schandau back to Litoměřice.

Reading

clearerthinking.org has nice tools, articles, and blog to help you make better life decisions.

Watching

The Gray Man, didn’t enjoy it, the only thing that made it bearable was that I was riding on zwift at the same time.

This month I learned

What happens when you swip a credit card
Agroforestry is a land use management system in which trees or shrubs are grown around or among crops or pastureland. Trees produce a wide range of useful and marketable products from fruits/nuts, medicines, wood products, etc. This intentional combination of agriculture and forestry has multiple benefits, such as greatly enhanced yields from staple food crops, enhanced farmer livelihoods from income generation, increased biodiversity, improved soil structure and health, reduced erosion, and carbon sequestration. Agroforestry practices are highly beneficial in the tropics, especially in subsistence smallholdings in sub-Saharan Africa and have been found to be beneficial in Europe and the United States.
gingerly - in a careful or cautious manner.

Listening

June

matousdzivjak@gmail.com (Matouš Dzivjak) — Fri, 01 Jul 2022 00:00:00 +0000

10th to 19th June we were in Austria with a very familiar group of cycling friends (Ondra and David). On Sunday we saw the MTB World Cup in Zell am See/Kaprun and the rest of the week we were cycling almost every day. I managed to squeeze in a few swims as well; in a wonderful outside pool. Last day we went for the classic Queen Stage, this time to Großglockner, and drove back home on the same day to have full Sunday for recovery.

＊

Week later, on 26th June, I finished my first Ironman. 3.8km swim, 180km ride, and 42km run. It was long, exhausting, hard, but most importantly fun.

Suprisingly, the swim went smoothly. My worst discipline improved a lot in last 4 months and I came out of the water fresh and ready for the 2 stronger disciplines which might have been a mistake. I pushed hard (too hard) on the bike for the first half of the 180km and the rolling terrain with a lot of steep small hills took its toll. On 100th kilometer I already knew that it will be a painful day. I spent the rest of the bike in damage-control mode and tried to conserve as much energy as possible for the run.

The run went horrendously. I started slowly at 4:50 pace and hoped to increase it slightly over the course but that didn’t pan out. At 16th km I completely bonked, I didn’t have energy, my stomach hurt, and it was very hard to consume any calories. I spent next 12km walking (even short jogs were impossible) until I recovered at least a little bit. Last 12km were finally something one could call a run.

I finished in 11:34:42. The heat made it one hell of a race as my heat tolerance is really low and I am still trying to figure it out and get used to it. On the other hand, it was an invaluable experience. I tried nutritioning on a really long endurance events. I tested out how fast can I go on the bike (went too fast). And I gained some confidence in the water. Still, the event left me a little bit dissatisfied so I decided to sign up for Ironman Barcelona in October.

Now some recovery and off to Spain for Ultratrail Val d’Aran in 12 days.

Reading

The Problem with Fighting Fires

The problem is that firefighting is thrilling and addictive and makes you feel needed–and installing smoke detectors is boring. The problem is that you’re really good at fighting fires.

Life Is Not Short

Everyone complains about how short life is, but that perspective is broken. Life is not short. The real issue is that we waste so much of it.

Why didn’t Gandalf own a Colt .45?
They’re Made out of Meat
How to fuck up an airport; i.e. how the BER Airport came to be

Watching

Stranger Things are back with 4th season and whatever, I will admit it, I enjoy it.

This month I learned

I read a bunch of articles on value of personal time and ended up on tool called What is your time really worth to you? - that helps you estimate how much money each hour is worth to you. My estimated value of free time is €39 per hour which seems about right or slightly lower than if I tried to estimate it without the tool.

It is very useful to know the value of your free time. It helps you make informed decisions in many situations such as:

deciding whether to order groceries online (with premium and delivery) or go to store
whether to take more expensive but shorter option of transport when traveling
whether to take additional part-time work

and much more. This all needs to be taken with a grain of salt as personal preferences come to play. Some people for example enjoy grocery shopping while others (🇬🇧) don’t mind waiting in a queue. Either way, the worth of your time if an interesting data point in decision making and it might make you reconsider a few decision here and there.

Listening

After a long time I had a few hours for podcasts while driving to Frankfurt, these two were the best:

No groundbraking music discoveries this month. Gleb (SK) release a new album that is… underwhelming. Anyway, here’s one of the songs I enjoyed this month:

May

matousdzivjak@gmail.com (Matouš Dzivjak) — Mon, 30 May 2022 00:00:00 +0000

On 8th May I ran my second Marathon after 2 years. I went into it with simple goal of finishing under 3 hours, not very confidently to be honest, and I managed to do so by the margin of 10 seconds. It was hard, and long, but most importantly hard. First 30k went smoothly but every easy kilometer made me more afraid of what is to come in the last 12k where everything is decided. Last 11k were the hardest and last 6k I my quads were in cramps.

The best decision was slowing down in the initial kilometers when the pacer for 3:00:00 time ran at higher pace around 4:05 min/km. And it paid off over the course of the Marathon when many people started slowly fading out while I kept my steady pace. I am very happy with the result, although I probably won’t aim for anything faster anytime soon. (with Berlin marathon in September I am sure I will change my mind though).

Special thanks goes to Dominik who supported me during the Marathon and made this whole thing work.

＊

Second week of May we had Hack Week with SumUp in Portugal. Initially, I was hesitant to come but now I am very glad I did. It was incredible. We had awesome team and worked on the SumUp for Developers project trying to bring our public API to better shape. I met a lot of people that I knew until this point by just their Slack handles and everyone, without exceptions, was friendly and fun to talk with.¹

Week of socializing was more than I did cumulatively over last 2 years. Little step outside the comfort zone but I learned a lot of intersting life stories of colleagues, something we wouldn’t usually talk about during our daily interactions. I build respect and admiration for many of the people I met and it left we contemplating: what do I want to do with my life?

If you are drinking Jägerbombs at your wedding you are too young to be getting married. …

＊

On 21st and 22nd we raced the Run Labe Run race. 377.5 km relay along the Labe river in team of 9 people. Everyone had 4 segments of varying length from short easy segments at around 7km, to hilly long segments of 14km+. We placed 9th out of 83 teams which is incredbile and we had a lot of fun. I managed to run my 5k and 10k PB at 18:57 and 38:57. The race was tough, I ran most of the segments at >163 BPM and managed to get 2:30 hours of sleep during the weekend. On the positive note it was a great leg-check before the Val d’Aran which now seems harder than ever, but hopefully doable.

Reading

What is a depressing truth you have made peace with?
A Simple Explanation of How Money Moves Around the Banking System
The Rich Are Not Who We Think They Are. And Happiness Is Not What We Think It Is, Either.
Not My Job. I will need to set a reminder to read this every once and then as I feel like our team is taking on a lot of work that could be delegated or rised higher.
Grandpa’s Basement House
Why do you waste so much time on the internet?

Loneliness. We don’t have meaningful social connections anymore like our parents or their parents geeration had. We are so scattered, that I am unsure how many of my friends are actually friends and how many are just professional contacts. Everytime I switch job, almost 70% of my friends suddenly fall out of contact. Heck, I don’t even know the people who live in next apartments both left, right, up and down on the same building. Socializing with my friends mean, setting up an appointment weeks ahead to see if we can align on a free-slot and this often involves all of us commuting to somewhere and disbanding by 22:00 hours because family, work next morning, chores to do, doctor appointment and other human things.

Food Security and the Coming Storm

Watching

Ironman World Championship St. George was fun and motivated me before the marathon I had next day.
Don’t chase happiness. Become antifragile | Tal Ben-Shahar | Big Think
Love, Death & Robots. After not-so-good 2nd season Love, Death & Robots earned my respect again. The third season is dark, fabulous, and original. My favorites were Bad Travelling, The Very Pulse of the Machine, Mason’s Rats, and Jibaro. Although, Zima Blue is still the overall winner.

This week I learned

Bosnian War, which was quite heavy read. I am not sure whether we skipped this topic during our history lessons in highschool or I just wasn’t paying attention.
jet-setter - a rich, fashionable person who travels a lot
Apple’s hidden flight tracker app

Listening

Can’t belive I am admitting it but I am now listening to techno DJ set by a colleague of mine on repeat: dunkeltudeln with hrmny @ VidaMar in Portugal.

Other than that I enjoyed following songs this month:

Stats

Special thanks to Ena, Stepan, Jullien, Connor, Vinny, Nico, and others that made the project work and thanks to whom I had more fun than I could possibly want. ↩︎

Our approach to Go APIs

matousdzivjak@gmail.com (Matouš Dzivjak) — Thu, 26 May 2022 00:00:00 +0000

It’s hard to mantain docs and code in sync. Best case scenario, you use one as the source of truth and generate the other. This works well for example for python where you can use apispec to annotate the API in a structured way. In Go, this was always a struggle. One of the favorite tools for this task is swag that can generate openapi specification from the code (based on annotations in comment). The issue is, using comments for specification doesn’t work well. The comments get very long, it’s hard to maintain readable structure, and you can’t distinguish between documentation (what will be public) and actual comments (internal to repository).

At SumUp we have recently have the biggest success with oapi-codegen. Here the order is inverted, you write the specification first and generate the code from there. oapi-codegen requires you to use either echo or chi framework, if neither suits you, you can still use it to at least generate the models.

Our approach currently looks like this:

First you add specification of your API in a spec package. Such as spec/openapi.yaml:

openapi: 3.0.0
info:
  title: Sample API
servers:
  - url: http://api.example.com/v1
paths:
  /user/{id}:
    get:
      summary: Get user.
      oprationId: GetUser
      responses:
        '200':
          content:
            application/json:
              schema:
                $ref: "#/components/schemas/User"
components:
  schemas:
    User:
      type: object
      properties:
        required:
          - email
        email:
          type: string

Next, you add gen.go file that will be used with go generate command to mantain the generated code up to date:

package spec

//go:generate go run github.com/deepmap/oapi-codegen/cmd/oapi-codegen --package spec -o spec.gen.go openapi.yaml

Now any time you update your specs you can run go generate ./... to also update the generated code. oapi-codegen will by default generate for you the types, client implementation, and server interface. You still need to implement the server side though, but that is fairly easy with all the generated code. You implement the generated interface:

package api

import (
	"github.com/labstack/echo/v4"

	"github.com/you/your_package/api/spec"
)

type Handler struct {}

func (h *Handler) GetUsers(c echo.Context, id string) error {
	return c.JSON(http.StatusOK, spec.User{
    Email: "test@sumup.com",
  })
}

And finally you register it on an echo router

package main

import (
	"github.com/labstack/echo/v4"

	"github.com/you/your_package/api"
	"github.com/you/your_package/api/spec"
)

func main() {
	e := echo.New()
  spec.RegisterHandlers(g, &api.Handler{})
  e.Start(":8080")
}

That’s it, you are ready to roll. This approach saved us a few headaches already.

April

matousdzivjak@gmail.com (Matouš Dzivjak) — Sun, 01 May 2022 00:00:00 +0000

First week of April I had the honor to best best man at my friends wedding. It was fun except the part where I had to do my speech and organize the activities during the evening. There are more weddings to come and even more children to be born. Which is intersting because I couldn’t feel less ready for such things in my life. Altough, saying such things as single person probably gives it less weight.

＊

Second weekend of April we had primary school reunion after 10 years. 22 out of 28 people came which exceeded all my expectations. Primary school reunions are fun because you get meet people from wide range of social groups. Some still studying, some already working for multiple years, some having children and weddings, and some you don’t really need to know more about.

There weren’t really any stories that would stand out but altogether, everyone seemed to be doing fine which I was glad to hear. I am looking forward to the next reuinion, what will another 10 years bring?

＊

Third weekend we were in Berlin with the sisters. Eating, walking, and eating some more. And the last weekend in South Czechia, cycling with the friends. Overall, fun month.

Reading

DALL·E 2 - AI system that can create realistic images and art from a description in natural language. Another masterpiece from the (not so) OpenAI.
The housing theory of everything
Imports do not subtract from GDP
A modern home
How Covid Stole Our Time and How We Can Get It Back slightly depressing but insightful read.

What it boils down to is this: My life, in the best-case scenario, will consist of around 20 years of in-person parent time. The first 19 happened over the course of my first 19 years. The final year is spread out over the rest of my life. When I left for college, I had many decades left with living parents, but only about one year of time left to spend with them.

This week I learned

Flashpoint - The point at which a situation turns critical, for example, resulting in violence. False vacuum decay

Listening

Stats

Good Economics for Hard Times

matousdzivjak@gmail.com (Matouš Dzivjak) — Sun, 01 May 2022 00:00:00 +0000

Abhijit Banerjee and Esther Duflo are masters of their subject. In Good Economics for Hard Times they examine the most pressing issues for human kind (climate, international trade, unemployment, migration) and while doing so they debunk a great number of fake facts surrounding these topics. Notably, contrary to popular believe migration is not on the rise and migrants do not steal jobs of the natives. Universal basic income does not make people stop working and lower tax rates do not keep the growth rate high, on the contrary, there’s high correlation between low tax rates and high level of inequality.¹

The book is humble and honest, admitting the wrongs economists made in a latest attempt to regain the public trust in their profession. Every chapter sheds the much needed light on the ever more important topics that will shape our future and the authors focus on the most vulnarble - poor, old, or otherwise disstressed people.

Banerjee and Duflo don’t refrein from sharing their views and politics. They want government schemas to help people move to areas with better jobs, to help them with changing professions if their field of work is on decline, and to provide the support universally as any conditions to the schemas tend to often unintentionally exclude people that need the help the most.

The human need for respect and sense of self-worth is what sticked with me the most. Poor or otherwise disadvantaged people don’t need only financial help but also sense of being worthy and having purpose to their life.

Notes

Comparative Advantage - the idea that countries should do what they are relatively best at doing. Oposed to Absolute advantage it suggests that even if one country is absolutely best at producing everything it will still end up specializing in the product where they have comparative advantage.

https://ourworldindata.org/grapher/inequality-of-incomes-chartbook ↩︎

Go generics: Baby steps

matousdzivjak@gmail.com (Matouš Dzivjak) — Sun, 03 Apr 2022 00:00:00 +0000

Generics have come to Go. One of the most radical changes to Go in years that sparkled a lot of heated discussions and took the frontpage of HN many times. The time has finally come to give it a try.

Generics

Go is a typed language, meaning that every value, variable, and function has a specific type (such as int or func (string) error). Until go 1.18 the only way to get around the type restrictions was to either use interface or generate typed code before compiling the binary. Since Go 1.18 there’s also third option, generics. Let’s take a look at a little example that we use extensively throughout our codebase.

package pointerx

func To[V any](v V) *V {
	return &v
}

func From[V any](v *V) V {
	if v == nil {
		var res V
		return res
	}
	return *v
}

This is a small convenient utility that helps converting from and to pointers. Previously, our implementation would have many of those function different only in the type that they take and return. For example String(string) *string to convert from string to pointer. We had to define one such function for each and every type that we wanted to convert to and from pointer.

With generics, this gets fairly easy and can be written in 10 lines of code. And it will work for any type that we might want to throw at it.

When to use generics

You most likely won’t need generics 99% of the time. There are only two large use cases where you should consider introducing generics: general purpose data structures (such as linked list, B-Trees, or hash maps - already part of language) and functions that work over language-definied container types (map, slice, channel).

Wrap Up

I am still very careful with introducing any generics into our codebase mostly because I believe that they are not needed in most of the cases and the potential for misuse often overweights the benefits. Here though, I must say I am glad that generics were introduced to Go as they make for nice and lean code.

February

matousdzivjak@gmail.com (Matouš Dzivjak) — Tue, 01 Mar 2022 00:00:00 +0000

Reading

Docs! Docs! Docs! by Brandur; how to create and maintain high quality API docs, the Stripe style.
Hello scientists of reddit, what’s a scary science fact that the public knows nothing about?
Stop Overusing the Outbox Pattern
How Does the FBI Art Crime Team Operate?
Big space Our planet is a tiny porthole, looking over a cosmic sea. Can we learn what lies beyond our own horizons of perception?

Watching

Modernizing a 20-year-old codebase with observability

This week I learned

Listening

Stats

How to Win Friends and Influence People

matousdzivjak@gmail.com (Matouš Dzivjak) — Thu, 03 Feb 2022 00:00:00 +0000

How to Win Friends and Influence People is book about things that we all know deep down there but need to be reminded of from time to time. The point the book is trying to convey boils down to simple observation: life is easier if you are making it easier for other people too. By appreciating, smiling, choosing the right words, not criticising, and taking other person’s needs into consideration.

In full honesty, I skipped a few pages here and there because the lesson of each chapter was conveyed by multiple examples and one was often enough to understand what is the author trying to say. The book isn’t groundbreaking in any way, the examples and stories are slightly historical, but the overall tone is heartwarming and the takeaways are true to the heart.

Notes

Fundamental techniques in handling people

Don’t criticise, condemn, or complain; instead, try to understand them, what they want and why they do things they do.
Give honest and sincere appreciation; try to figure out other person’s good traits.
Arouse in other people an eager want; don’t force your ideas on others, make them want to be part of it.

How to make people like you

Become genuinely interested in other people; people are interested in others if they are interested in them.
Person’s name is to them the sweetest sound in any language; calling people by their name has its powers.
Be a good listener; by encouraging others to talk about themselves and their needs.
Talk in terms of other person’s interest.
Make the other person feel important, and do it sincerely.

How to win people to your way of thinking

You can’t win an argument; the only way to get the best out of it is to avoid it.
Show respect for other person’s opinion; avoid saying “You’re wrong”.
If you are wrong, admit it.
Begin in a friendly way, and handle situations calmly; being rude won’t get you anywhere.
Get other person to say yes; give leading questions that have yes answers and work your way up to the final yes to what you really need.
Let the other person do the talking; it might give you more information to work with or if nothing else you will make them happy.
Let the other person feel that the idea is theirs; by planting the ideas and letting others to develop them on their own.
Try honestly to see the things from the other person’s view.
Be sympatethic with the other person’s ideas and desires.
Assume the best about everyone.
Dramatise your ideas.
When nothing else works, throw down a challenge.

Be a leader

Begin with praise and appreciation.
Call attention to people’s mistake indirectly; hint at the mistakes, let people realize them on their own.
Talk about your own mistakes first before criticising others.
Ask questions instead of giving direct orders.
Let the other person save their face; destroying someone’s ego doesn’t do any good.
Praise the slightest improvement and every improvement.
Give the other person fine reputation to live up to.
Use encouragement. Make faults seem easy to correct.
Make the other person happy doing the things you suggest; consider what they gain from it and specifically convey it when making a request.

January

matousdzivjak@gmail.com (Matouš Dzivjak) — Tue, 01 Feb 2022 00:00:00 +0000

I’ll be running Val d’Aran Ultratrail on July 7th, 2 weeks after Ironman Frankfurt (duh). The race is 105 km long, has over 6000 m elevation gain, and takes place on the Spanish side of Pyrenees. If I am able to finish the race, I will be able to enter the draw to participate in UTMB next year which would be the ultimate goal. But, with that I am getting ahead of myself, first I need to get a lot of volume into the legs that didn’t even fully recovered from the cycling camp in Spain.

As a side note; I also got my entry in Berlin Marathon and I still have my entry from previous year to the Prague Marathon. This year will be heavy and it’s about the time for me to learn to recover properly which I hope will be easier thanks to the new addition into my clever wearables; whoop.

And as a second side not; I also signed up for the DoloMythesRun, ultramarthon (60k) in Dolomites, Italy. It will take place 2 weeks after the Val d’Aran Ultratrail that takes place 2 weeks after Ironman. I think I should start training recovery.

＊

This blog got a little rework, I moved the navigation to the side on large screens to make better use of the availanle space. The colors have also changed slightly, instead of raw black and white this website now uses off-colors that I sunjectively find more pleasant to the eye.

＊

My wrist started hurting lately, especially after prolonged periods of working (programming) so I decided to switch to split keyboard. After some research and a few hours of contemplating whether 300$ is a justifiable price for keyboard I ended up ordering the Ergodox EZ. As of writing this pragraph I am on my 3rd day with the keyboard, still early in process of getting used to grid layout and other nuances of not having your hands close together anymore. The biggest difference so far is using the thumb for multiple things not just the space bar. The other significant difference is the grid layout; I still struggle to hit z and q precisly. And last but not least, I still need to figure out where to bind the brackets to to make them easier to work with.

＊

One of the greatest pleasures of this month was learning about MIT Mystery Hunt, puzzlehunt competition taking place yearly on the MIT campus during the Martin Luther King, Jr. weekend (January). The competition started in 1981 and currently attracts more 2000 participate every year. I spent some time in the evenings this month reading about individual years and going through some of the puzzles and oh boy… if there ever was definition of nerdy it would be the MIT puzzle hunt. The puzzles are wonderful, clever, with tons of pop culture references as well as remarks to scientists, artists, and wide variety of niche topics from nautics, to biology and music. And they are hard, MIT hard. For reference, there’s usually over 100 puzzles varying in difficulty and it takes the best teams around 2 to 3 days to solve all of them, and we are talking about teams composed of MIT profesors and teachers, without too much exaggaration the brightest minds you could possibly put together.

My favorite so far was 2021 hunt titled Yew Labs that has whole RPG game built with NPCs or MIT students and teachers.

＊

How do we learn useful things?

Observations (collect data, ask questions, find patterns)
Models (build model & theory, try to explain, find out what’s repeatable and what’s random)
Observations (verify predictions, find your error, confirm your theory)
repeat

Reading

How Google’s Marissa Mayer Prevents Burnout
larvalabs/cryptopunks; seems like the trend of NFTs is not going away anytime soon, contrary it keeps rising. So here I am, reading the source of cryptopunks to learn more.
Bitcoin: A Peer-to-Peer Electronic Cash System (whitepaper)
Gorillas: Special offer - unicorn slices, 150g 🦍❤️ - By reverse engineering Gorillas (delivery company) app and API zerforschung found out, that they are basically leaking all user info. Consider me surprised.
GPS by Bartosz Ciechanowski about one of the greatest inventions of late 20th century.
Math Foundations from Scratch; price manipulation in crypto markets.
Axie Infinity: Infinite Opportunity or Infinite Peril?
Economics of Minecraft

Watching

The long run, an inside view - about long runs with the most famous and humble athletes in the world.

Everybody is free, in long runs you don’t have captains, we don’t have bosses but we have leaders and we expect everybody to be a leader in his own capacity and to be in charge of the long run. We don’t train people to perform or finish long runs but we train people to be human beings when they are running around Eliud Kipchoge

Line Goes Up – The Problem With NFTs, a case against crypto and NFTs. Even though the video has over 2 (two) hours it is already so condensed and rich on fact and information it will get you hooked.
Margin Call, I loved Big Short I love this too.

This week I learned

Negative zero exists (in computing) and is standardized by IEEE 754.

Listening

Stats

Learning Math

matousdzivjak@gmail.com (Matouš Dzivjak) — Tue, 01 Feb 2022 00:00:00 +0000

I decided to do a little math refresh and revisit all I have learned since kindergarten up until now, focusing on topics that I know I have shortcoming in and topics where I struggled the most (looking at you Mathematical analysis).

To make the journey useful also to others, I decided to create a list of the resources that I found interesting, helpful, and well written. That being a highly subjective measure take this whole list with a grain of salt and in case of need refer to the Additional Resources section at the bottom of the page.

Areas of Mathematics

Foundations

Math Foundations from Scratch
Understanding Mathematics; Links to resources talking about how to understand mathematics, mathematical language and mathematical notation.

Algebra

Linear Algebra

Topics:

Resources:

Calculus & Analysis

Topics:

Resources:

Probability & Statistics

Introduction to Modern Statistics (2nd Ed)

Discrete mathematics

Number theory

Additional resources

Becoming a Supple Leopard

matousdzivjak@gmail.com (Matouš Dzivjak) — Wed, 12 Jan 2022 00:00:00 +0000

Becoming a Supple Leopard is a guide to injury prevention, mobillity, athletic performance, and overall well-being. Dr. Kelly Starrett himself mentions right at the beginning of the book that it is not meant to be read in whole from the beginning to the end but rather referred to to resolve specific problems or find inspiration and learning on specific areas of the body.

December

matousdzivjak@gmail.com (Matouš Dzivjak) — Mon, 03 Jan 2022 00:00:00 +0000

I was neglecting this blog a lot lately, contrary to what I promised myself at the beginning of the year. But, I will try and catchup now, most importantly with 2021 review and stats and with a few book reviews missing, hold on tight.

＊

I tried to answer the life long question of How much abuse can your body take before it starts falling apart, the answer is more than 34 days. 34 days is exactly for how long I have been in Spain and for how long I have been training with exactly 1 rest day. I felt well and strong for most of the time, until I returned home and finally let my body rest. My legs refused to walk downstairs for 7 days and I had problems with any downhill terrain for over 2 weeks. The month of physical strain I put my quadricepses through left my with a case of Crush Syndrome. Overworked tissue of my leg muscles started breaking down and my body didn’t have enough time to recover accummulating large amount of residuals before it could finally let it float out.

Tissue naturally breaks down and rebuilds over time. When the breakdown process is speeded up through crush injury, strenuous exercise, or medications it results into Rhabdomyolysis - rapid breakdown of muscle issue. Strongest indicator and most reliable indicator of Rhabdomyolysis is the level of Creatine Kinese in blood. Normal level of creatine kinase in blood is 200 to 400 units per liter. For male athletes the upper bound can be around twice as high, up to 1000 units per liter. My stupid training approach lended me on 40,000 as measured from my blood sample week after I returned.

Needless to say I am going to pay much more attention to recovery from now on. Furthermore, I might as well stay in the endurance zone next time instead of having yet another dick-measuring contest on uphill segments with guys that are far above my performance level. And last but not least, this makes me want to learn more about the physiology behind my training, because so far I focused on the big picture of optimal training splits, heart rate zones, and performance measures completely neglectic the most important part - my body.

Reading

Starship is Still Not Understood - the economics behind Starship, how it hompletely changes the space industry, and all the other implications of cheap cargo transport into the low Earth orbit.

Starship is intended to reach numbers as low as $1m/T and 1000 T/year for cargo soft landed on the Moon. Apollo achieved about $2b/T and 2 T/year for cargo soft landed on the Moon. Starship is Still Not Understood by Casey Handmer

Death Note: L, Anonymity & Eluding Entropy by Gwern - analysis of the deathnote using Informatioin theory.
Ad Astra - The coming battle over space by Rachel Riederer (report). Why we need Outer Space Treaty and why sattelites are the current Achilles’ heel of technologically advanced nations.
Moo Card Player - NFC physical medium for music
100 years of whatever this will be - “in any system, if you don’t have an explicit hierarchy, then you have an implicit one”
Lesswrong
Sacrifice by Tynan

Watching

Pixer’s Soul probably wasn’t bad but either I missed the point of the movie or I wasn’t focused enough to understand it. Soul reminded me of my favority Inside Out that is already 6 years old (feels like yesterday). I think I owe this movie one more chance but lets leave that for when I have someone to watch it with.

14 Peaks: Nothing Is Impossible is finally giving the Nepali mountaineers and sherpas the recognition that they deserve in a movie about probably the greatest mountaineering feat of 21st century so far. I loved the movie, it’s heartfelt tone, and the beautiful imagery of the most impregnable parts of the Earth.

Don’t Look Up had a great concept but I wasn’t fond of the pacing of the movie.

Listening

Stats

2021 Review

matousdzivjak@gmail.com (Matouš Dzivjak) — Sat, 01 Jan 2022 00:00:00 +0000

That was fast (she said). 2021 was great, I give it 5/7. In brief, I ended my career at Kiwi.com and moved to Berlin to work at SumUp. I spent a lot of my time doing sports, with friends, and sometimes both at the same time. I did two half-ironamns, week apart, a 275 km long ride, and spent 45 days training in Spain. And in no particular order: visited Portugal, did a few backcountry skiing trips to Krkonose, went to Mallorca for a cycling trip (twice), rode from Berlin to Czech republic, and climbed Glossglockner. Before we get into the numbers, thank you all that made this possible: my family and friends.

Sports

My legs are still recovering, liver is slowly catching up, but I am already ready to share my sport stats for last year. 2021 was huge, 691 hours huge. I was active 317 days, 50 up from the previous year. My running volume went up (178 runs, 2 283 km, 178.5 h), cycling volume went way up (148 rides, 11 521 km, 398.5 h) mostly thanks to switching to road bike, and swiming improved slightly (31 swims).

I had 2 training camps, one of them was 35 days long and almost killed me. I spent both training camps in a company of great people. Ondrej has over 20 000 km this year, David is racing all around the europe, and Zuzane is regularly placing in top 3 in the Czech Kolo pro Zivot series. Needless to say, I have a lot space to improve but in this company it is easier than ever.

Facets, elevation plots, and heatmap of my activities.

And what does my review of 2020 has to say about this year?

I hope to keep the pace even the next year and would love to pump those numbers up a little bit more. The goal is to run 1875km (5km a day), ride 3650 km (10km a day) and swim 365km (1km a day). Those targets are quite low because I don’t want to stress myself and I will go for more either way. I would also love to run the sub-3 marathon and finish a full Ironman race.

“run 1875km (5km a day)” done, “ride 3650 km (10km a day)” done done, “swim 365km (1km a day)” not even close. “sub-3 marathon” nope, I didn’t even try, not sure if I would be able to pull it off but one way or the other I have at least one marathon scheduled for this year (Volkswagen Prague Marathon, 8th May) so there’s no more excuses. And last but not least “finish a full Ironman race” - I didn’t, but as with the marathon I have a full distance Ironman scheduled for this year (IM Frankfurt, June 26th).

I didn’t follow the goals very closely but overall I am satisfied with my training this year, I improved a lot in cycling and swimming. I am not sure where my running stands as of now as I did only a single running race this year (although it went well and I ran one of the best times). But most importantly I rarely needed to persuade myself to train. I loved every single bit of it and want to continue with this mentality. After all, I am doing this for myself, and whatfor if not for enjoyment and happiness.

Here are my take-aways for next year:

Find a coach. There’s only so far I can improve with ad-hoc training. I always try to give the training a structure and split it reasonably between all the sports that I want to do. Although, unintentionally I avoid things I am bad at and I do more of the things where I feel fit and strong, such as long rides. I think having a coach, even if only for creating a training plan, would help me focus on my weaknesses and gain more from the sessions that I do.
Improve the swim. I came to terms with not beeing the biggest fan of swimming altough I enjoy it more as I improve. Yet, I am still terrible and slow and I don’t feel confident swimming 3.8 km this year. I plan to join a few weekend training camps and swim at least a little bit more than the last year. The biggest achievement would be to swim at around 1:45 pace at the end of the year and have over 182.5 km.
Keep going. This one is the most important one for me. I want enjoy the training sessions the way I do now. This year with a slightly bigger focus on recovery and overall healthiness, but still pushing the limits. No matter if I put more hours in or less, lets keep the enjoyment as primary goal (maybe right after smashing all of my PBs).

Finances

I saved 18.469 € this year, around 39% of my income. This is great achievement in many ways. First, it is 3 times more than last year. Second, 39% is awesome and I am proud I was able to keep it that high. Ideally, I would be putting aside around 50% but given how much I spend on sports, food, and coffee I find this a reasonable cut.

This year, same as the previous one, my biggest expense were sports. Cycling is again leading with over 5.000 € this year and that’s without the new bike that I got through bike leasing benefit at work. The rest of the sports is far behind - triathlon on the second place with 1.100 €, most of that race entries and on the third place is running at 900 €.

Other than sports I spent 6.700 € on living (rent, energies, furniture, etc.), 3.300 € on food of which only 600 € on eat outs, 1.000 € on clothing and 500 € on coffee.

How does that compare to 2020? My spendings went up 7.000 €, from 21.000 € to 28.000 €. Sports were cheaper this year whereas living skyrocketed into the second place since I moved to Germany. Food hoveres around the same amount and travel expenses went from less than 1.000 € to over 4.400 €, no regrets though.

Last year I wrote “This is definitely the biggest goal for next year - safe more.” and I think I fullfilled my goal. Currently I feel like I am striking the perfect balance between saving, and buying stuff I find worth it, inclining slightly more to the later than to the former. I intend to keep this up and if possible bring the savings ratio to 0.5 of my income.

2022

There’s not much I expect from 2022 and if it goes as well as this year I will be satisfied. Given the recent experience with over a month in Spain I would like to visit Girona, come back to Dénia, and spent a few weeks running and cycling in Austria.

If you endured up to this point - thank you, I wish you a lovely year.

Invisible Women

matousdzivjak@gmail.com (Matouš Dzivjak) — Mon, 06 Dec 2021 00:00:00 +0000

TODO

November

matousdzivjak@gmail.com (Matouš Dzivjak) — Wed, 01 Dec 2021 00:00:00 +0000

I though the cycling season is ending for me but it turns out this is not that case. We left for Mallorca on 12th for the second time this year. As is customary, the weather wasn’t ideal first couple of days. It was rainy and windy so we spent most of the time in the southern part on the flats. When the weather finally improved we were so hungry for the hills that we ended the training camp with 3 successive days in the hills. One of the rides being rough 200 km long stage with 2770 m elevation gain, combining 3 beutiful climbs: Lluc, Formentor, and Bethlem. Overall, I felt way stronger than in March when we were first time here. Strava suggests that most of my climbs were slower but I attribute that to a few factors. First, it’s the end of the year and the body took a lot of beating without any rest what so ever. Secondly, compared to the previous training camp I was riding on way lower heart rate, spending most of the rides in comfortable endurance zone. And last but not least, Ondrej Prenek wasn’t with us, thus we didn’t have dick measuring contest on every single climb.

I was supposed to fly back to Czech republic on 22nd November with the rest of the group but I changed my mind. A friend of ours owns an apartment in Dénia (Alicante, Spain) where they spent a lot of time in the summer, not in winter though which came in handy. Instead of flying back home I and David took a ferry from Palma de Mallorca to Dénia where we are currently staying and riding (and will be for another 15 days).

I didn’t hear much about Dénia before but it lays close to Calpe, one of the best cycling destinations in Europe frequently visited by pro tour teams. The city is pretty much ghost town during this time of the year with most shops being closed or having reduced opening hours compared to the summer. During the summer season Dénia’s population jumps from the stable 40,000 to well above 200,000 making the city a party town on the level of Ibiza and similar. Compared to Mallorca the weather seems to be stable here with temperatures around 15 °C, days are sunny and slightly longer than what we could enjoy back in Czech republic. My only complain is the perpetual wind that makes every ride a hard ride. So far we are sitting at around 2000 km in last 18 days but my legs still feel fresh and I can’t wait to explore more of what Dénia has to offer.

Reading

Going mouseless - tiny guide to going fully mouseless
Against Individual IQ Worries

Watching

The Guilty by Antonie Fuqua. I am huge fan of Jake Gyllenhaal, especially after seeing his performance in Nightcrawler and Prisoners, thus this movie was a must. The whole movie was dialog driven and must have been very cheap to produce (excluding Jake’s payroll). Jake’s performance was stellar as always but the movie didn’t drag me in and didn’t make me feel very connected with the characters. I would rate it at around 6/10 - not great not terrible, neverthless not a movie I would like to see again.

Listening

Stats

Freakonomics

matousdzivjak@gmail.com (Matouš Dzivjak) — Wed, 24 Nov 2021 00:00:00 +0000

TODO

October

matousdzivjak@gmail.com (Matouš Dzivjak) — Mon, 01 Nov 2021 00:00:00 +0000

I ran my strongest run to date. 23.38 km, 423 m elevation gain, 4:40 avg. pace and 162 avg. heart rate. I don’t think I ever held my heart rate over 160 bpm for 1 hour, yet alone 1 hour and 48 minutes, and I hope I won’t ever have to do that again. The run was part of Run Berounka Run, a trail running relay following the Berounka river in south-western part of the Czech republic. Verča invited me to the race 2 weeks prior so I had around 0 preparation in terms of long distance tempo running. But, I would be lying if I said that more time for preparation would make me train for it. Either way, I enjoyed the race greatly. It was very different from any other race I did up to date. The scenery, route, and perfect pacing all added up to the best run I ever had. In the end, we finished in 17th place out of 49 teams and I had second best time on my segment. Looking forward to more running races next year, and maybe finally even the sub-3 marathon.

Watching

Dune by Denis Villeneuve, is this my new favorite movie? I am huge fan of Denis Villeneuve. From Prisoners and Sicario, to Arrival and Bladerunner 2049, Denis is mastermind of storytelling and great visuals and now I can’t wait for the part two to be out. (Did I forgot to mention the score by Hans Zimmer?)

Listening

Stats

Net Worth: €21521.65 (+€1792.22)

Running: 13.56 hours, 172.07 km, 13 runs

Cycling: 19.98 hours, 632.7 km, 5985.8 m ↑, 10 rides

Swimming: 3.58 hours, 11.02 km, 6 swims

Activity Totals: 42.25 hours, 824.72 km, 38 activities

Body Stats

Body Weight: 79 kg

Body Fat %: 13.2%

VO₂ MAX: 59 ml / min / kg

September

matousdzivjak@gmail.com (Matouš Dzivjak) — Fri, 01 Oct 2021 00:00:00 +0000

Road to Ironman

Two half Ironmans done this month. Czechman, the biggest Czech race with over 500 people in the starting field and Doksyrace that I already attended last year. As usually both with terrible swim and by terrible I mean bottom of the bracket terrible. One might expect that consistently failing in single discipline will teach me a lesson and motivate me to get working on it but that’s not the case. I still go to the swimming pool ones or twice a week at best and consider that good enough. And I am afraid it will stay this way until it’s too late and there’s one month left until…

Ironman Frankfurt. Yes, I registered for full distance Ironman next year in June. Do I know what am I getting myself into? Vaguely. Will it hurt? Definitely. Will I improve my swimming until then? Most likely not. The target is not to set any targets and to finish the race. Given the distance (3.8 km swim, 180 km cycling, 42 km run) this means conservative tempo and great nutrition plan execution. My experience from both half Ironmans this month is experience of excruciating stomach pain during the run and I don’t want to go through that on a Marathon distance run after 6 hours of racing give or take.

Grossglcokner

Glossglockner, at 3,798 m elevation, is the highest peak of Austria and also the highest peak I ever climbed. The peak was first ascended in 28th July 1800 by a local priest and 4 peasants and carpenters and made widely touristic by the construction of scenic High Alpine Road between 1930 and 1935.

Liquicity

Liquicity label held the first festival after 574 days long sabbatical. Maduk, who hosts and headlines this yearly event was missing, but his replacement Andromedik, the new Belgian young gun, didn’t disappoint. As is the custom, liquid genre was long gone by 2 am in the morning and for the rest of the night one could hear mostly Neurofunk with occasional breaks into other drum and bass sub-genres such as Jump Up or Jungle.

Reading

Spotify Research
We’re living in the age of naive cynicism
Lowbeer’s Tipstaff; Cool Tools all the awesome stuff they have and do at Stripe, written by Brandon in the nanoglyph newsletter
Understanding How Facebook Disappeared from the Internet - the 4 hour long Facebook outage explained.

Watching

Listening

Coffee

Kenya by Zoban, already too dry to be good

Stats

Net Worth: €21521.65 (+€1792.22)

Running: 13.56 hours, 172.07 km, 13 runs

Cycling: 19.98 hours, 632.7 km, 5985.8 m ↑, 10 rides

Swimming: 3.58 hours, 11.02 km, 6 swims

Activity Totals: 42.25 hours, 824.72 km, 38 activities

August

matousdzivjak@gmail.com (Matouš Dzivjak) — Wed, 01 Sep 2021 00:00:00 +0000

Long-form journalism is a branch of journalism dedicated to longer articles with larger amounts of content. Typically, this will be between 1,000 and 20,000 words. Long-form articles often take the form of creative nonfiction or narrative journalism. Wikipedia

An editor-at-large is a journalist who contributes content to a publication. Sometimes such an editor is called a roving reporter or roving editor. Unlike an editor who works on a publication from day to day and is hands-on, an editor-at-large contributes content on a semi-regular basis and has less of a say in matters such as layout, pictures or the publication’s direction. Wikipedia

Reading

[On Writing Well]({ {< ref “/books/on_writing_well” >} }) by William Zinsser
The 10-minute Mecca Stampede that made History by Williem Langewiesche
The Man Who Pierced the Sky by Williem Langewiesche
The Pirate Latitudes by Williem Langewiesche
The Incredible Rise of North Korea’s Hacking Army by Ed Caesar

Watching

Euphoria

Listening

Coffee

Kenya by Zoban, already too dry to be good

Stats

Net Worth: €19729.43 (+€497.7)

Running: 15.69 hours, 196.42 km, 16 runs

Cycling: 17.57 hours, 506.63 km, 5899 m ↑, 6 rides

Swimming: 1.06 hours, 3.2 km, 2 swims

Activity Totals: 44.37 hours, 729.64 km, 35 activities

July

matousdzivjak@gmail.com (Matouš Dzivjak) — Sun, 01 Aug 2021 00:00:00 +0000

Berlin is a wonderful city, yet far from feeling like home. Moving was hard, after 1.5 year of daily routine optimized to perfection I feel like the day is suddenly half as long and every chore takes twice the time it used to. Yet, I don’t want to judge before the dust settles in. So except to see more in following months, and hopefully before the Christmas, I will have some coherent opinion formed.

＊

This month was mostly work-focused. Compared to the last months at Kiwi.com at SumUp there’s more things to do than what can be done. Sometimes it is hard to not feel split between too many tasks and keep the focus. On the other hand, the problems at hand are fun and challenging. We are building identity system, authentication, and authorization system to replace the existing one. And while at it, we push for better practices and sense of responsibility, both lacking behind as of now.

I enjoy the solve things by talking with the people culture. It feels easier to establish a common ground and focus on things that need to be done when you can discuss what matters with all interested parties. Thanks to Julien I also started to get into the habit of taking notes during the meetings, refining them afterwards, and preparing talking points for the meetings to come to keep them to the point and concise. I also have the opportunity to work on diverse set of tasks, from backend development and software reliability engineering to frontend stuff and project managing.

On the other hand, I miss the overly open culture of Kiwi.com. There’s far less open discussions, off-topic channels, and friendly chatter at the SumUp slack. Although this seems to be compensated by the physical interactions, I would still appreciate seeing the It’s Wednesday my Dudes memes in #offtopic, discussions of every possible HN article in #devs-offtopic, newcommers introducing themselves in #devs-talk and people sharing their happy stories in #happy. Another thing I struggle with is getting feedback and seeing a clear path on the way to senior-ish role, this is on me though.

I will write more about the culture differences and the numerous other things about SumUp that I enjoy in future posts. To preface it though: I’m proud to part of our team and I hope I will be able to soak in as much experience and skill from the guys as I possibly can.

On a different note, I did a solo 275 km ride from Berlin to Litomerice (almost). It wasn’t as hard as I expected. I took off at 5 am. First 200 km went smoothly as I cruised at comfortable speed of around 31 km/h. I stopped every two hours only to refill my two small 550ml bottles and eat something that wasn’t carbohydrate gel or salted roasted cashews.

The roads were flat, with the kind of flat asphalt that is so smooth that the only thing you can hear is the rolling resistance of the tires. And than there was the polar opposite. In many villages they didn’t bother and kept the stone pavement, famous roubaix terrain, the stones that were put in place long before the first Kebab shop opened. But there’s no stopping for set of strong legs and one butt soaked in chemonix cream.

It all went downhill when I came to Dresden. The wind started blowing into my face with force that slowed me down to 20 km/h which felt like a snail speed. The weather was scorching and last drop of isotonic drink went down my throat before I even left the Berlin suburbs.

I managed to climb the two climbs parting me from the German-Czech border before I puked. From there, long descent followed into Usti nad Labem, our frequent stop for short and easy coffee rides. But the energy was depleted and I couldn’t even thing of consuming anything else than water. 20 km was parting me from Litomerice, my hometown and the finish of this crazy ride, when I decided to call parents to pick me up.

There I laid, next to the road, two empty bottles, 275 km in the legs, contemplating the meaning of life and everything and telling myself what a terrible and painful experience it was, and how I can’t wait to do it again.

Reading

Educated by Tara Westover
How to Work Hard by Paul Graham
On Writing Well by William Zinsser. Continuation of my path to better writing. A journey I embarked on with Sense of Style by Steven Pinker

Watching

Listening

Coffee

Kenya by Zoban

Stats

Net Worth: €18891.82 (+€2395.04)

Running: 13.9 hours, 178.05 km, 13 runs

Cycling: 46.45 hours, 1341.75 km, 11183 m ↑, 16 rides

Swimming: 1.12 hours, 3.35 km, 2 swims

Activity Totals: 63.75 hours, 1534.16 km, 35 activities

Educated

matousdzivjak@gmail.com (Matouš Dzivjak) — Sat, 17 Jul 2021 00:00:00 +0000

Tara was raised in a strict Mormon family, with bipolar father, sociopathic brother, and mother that turned her back on anything that was happening under her nose. Despite the odds and starting school at 17 Tara received doctorate form history at Cambridge.

Educated is wonderful book full of events that seem to be too insane to be true. Heartwarming and heartbreaking at the same time. Memoir of how far can one get despite the odds and how much our family and childhood narrates our life.

June

matousdzivjak@gmail.com (Matouš Dzivjak) — Thu, 01 Jul 2021 00:00:00 +0000

Reading

Watching

askdjaslkdjalda

Listening

Coffee

Stats

Net Worth: €16563.31 (+€5283.17)

Running: 16.83 hours, 221.16 km, 18 runs

Cycling: 33.02 hours, 1023.1 km, 11792 m ↑, 14 rides

Swimming: 4.35 hours, 12.42 km, 7 swims

Activity Totals: 58.9 hours, 1256.68 km, 44 activities

May

matousdzivjak@gmail.com (Matouš Dzivjak) — Tue, 01 Jun 2021 00:00:00 +0000

This was my last month at Kiwi.com. After almost 2.5 years I am bidding farewell and starting a new journey at SumUp. While I don’t feel particularly moved by leaving I am incredibly grateful for the time I spent at Kiwi.com. I learned a lot, gained a lot of experience and most importantly, bootstrapped my career.

Returning old laptop and migrating to new one left me with a few precious files less. I’m considering backing up the whole laptop to one place or the other, so far, Backblaze seems like an optimal solution for me. I wrote a short post summarising current options for periodical MacOS backups.

This month I started learning rust to extend my portfolio of languages at hand. So far I enjoy rust greatly, it plays well into my weakness for fast, clean, concise, compiled languages. I started by implementing the Tiny Renderer which serves as a nice tiny intro into how OpenGL and software rendering works. I wanted to try this project myself for a long long time and by writing the solution in rust instead of C++ I can kill two birds with one stone. I made my solution public on GitHub: matoous/runderer and will come back to it later to fix all the issues and bad practices when I have more experience with rust.

Reading

Mailbag #2, AMA by Tim Urban.

Watching

Love, Death & Robots volume 2, sadly underwhelming after the bar set by the first season. I mostly miss the deeper stories of the volume 1 such as Beyond the Aquila Rift or Zima Blue, volume 2 had only a few memorable episodes, specifically: Pop Squad, Snow in the Desert, All Through the House, and The Drowned Giant. Anyway, not all hopes are lost as volume 3 is already confirmed and in making.

Listening

Coffee

Stats

Net Worth: €11182.14 (+€1486.04)

Running: 15.55 hours, 200.5 km, 16 runs

Cycling: 37.31 hours, 1039.57 km, 12762 m ↑, 13 rides

Swimming: 1.14 hours, 2.96 km, 3 swims

Activity Totals: 69.21 hours, 1510.14 km, 46 activities

Back up your MacOS

matousdzivjak@gmail.com (Matouš Dzivjak) — Sun, 23 May 2021 00:00:00 +0000

I lost some of my precious data and config files while migrating to new laptop which brings me to the importance of having a backup. I did a little research on the current options for MacOS and ended up with 3 reasonable solutions; Time Machine, Backblaze, or Borg.

With my current iCloud setup, only the Documents and Desktop folders are synced to iCloud which leaves out my code directory and dotfiles. I am not that worried about the code folder as everything is versioned at GitHub and I push quite frequently, on the other hand, loosing this directory would mean loosing around 12 GB of machine learning datasets I accumulated either for side projects or diploma thesis. This alone should be a big enough reason to start backing up the whole laptop, not to mention the valuable dotfiles. For those I used Mackup, tiny utility to backup and sync application settings using one of the many storage providers (Dropbox, Google Drive, iCloud, etc.). Mackup works great, is maintained and stable, the issue is, it doesn’t understand custom config files unless you explicitly tell it to. Which I didn’t. So during the migration I lost all of my zsh configuration files (whole .config/zsh), and a few, less important files such as global gitignore. There are more flaws with Mackup from my point of view, it backs up whole application configuration folder including log files, lock files, and temporary files making the backup bloated. You also have to verify that indeed everything that you want it to backup is actually backed up or you might end up like me and loose part of your configuration because you had wrong assumptions about what will and what will not be backed up.

Time Machine can back up your MacOS device to external hard drive, other apple device, or NAS. That’s not a lot of options to choose from. On the other hand, Time Machine comes integrated with iOS devices and will always work just fine. In this case, the best option to me seems having a NAS at home and also backup the NAS itself to some cloud provider to follow the 3-2-1 rule of backups.

Backblaze is a cloud back up solution priced at $60 per year. Similarly to Time Machine it backs up your whole workstation. The backups are handled using native software, Backblze automatically encrypts all the files and has additional support for custom personal keys. At $60 it is significantly cheaper than buying NAS (given the sole purpose of the NAS would be to provide storage for the Time Machine backups). Backblaze seems like awesome solution if you want plug (read download) and play solution. There are also a few similar products you might want to consider: Arq priced at $49.99 a year but with limited feature set compared to Backblaze. IDrive at $52.12 a year but with limited storage size. Carbonite priced at $83.99, also with less features than Backblaze. And a few other options. Overall, based on the reviews features comparison, and pricing, Backblaze seems like the best option for easy backups.

Last but not least there’s Borg and restic. Both CLI tools/programs that can backup to countless storage providers. Both need to be told what to back up and where and neither runs automatically so you would have to solve that part yourself or find an existing solution, such as luispabon/borg-s3-home-backup. The costs are harder to calculate as they will depend on the amount of data you have, how often you will be backing up and the storage you would like to use. Anyway, they will be most likely lower than if you use one of the back up solution providers.

Overall, it comes up to how much effort are you willing to put into setting up the back ups (none - Backblaze or Time Machine, a lot - custom solution with restic), how much are you willing to pay (I don’t care as long as it works - Backblaze, I already have a NAS at home or want to buy one - Time Machine, I am willing to backup to external hard drive - Time Machine, the least amount possible - custom solution with restic), and how much you value your data (a lot - whatever backup suits you, not a lot yet - come back later).

Localization in a few lines of code

matousdzivjak@gmail.com (Matouš Dzivjak) — Thu, 13 May 2021 00:00:00 +0000

In computing, internationalization and localization are means of adapting computer software to different languages, regional peculiarities and technical requirements of a target locale. Wikipedia

XKCD #1179 by Randall Munroe

This is a tiny script that I initially used on this blog to localize dates. Shortly after I realized that it is really unnecessary as there’s only a single correct date format. Anyway, your idea of the perfect date might be wrong so here’s the code:

const lang =(navigator.languages && navigator.languages.length && navigator.languages[0]) || navigator.language || 'en';
const timeFormat = new Intl.DateTimeFormat(lang, { year: 'numeric', month: '2-digit', day: '2-digit' });
document.querySelectorAll("time").forEach(t => {
    t.innerHTML = timeFormat.format(new Date(t.getAttribute("datetime")))
})

April

matousdzivjak@gmail.com (Matouš Dzivjak) — Sat, 01 May 2021 00:00:00 +0000

I started building my personal knowledge base/wiki - wiki.dzx.cz. The wiki is heavily inspired by Everything I know by Nikita Voloboev, although I initially planned to use Notion for the purpose it is missing sidebar for easy navigation.

April was in the name of sports. I finished with 27 active days for the total of 67 hours, keeping the bar high after Mallorca. My Achilles tendon is soar and running is still impossible or very unpleasant but slowly getting better. On the other hand, my cycling performance is better by the day.

Oh, and we did this crazy thing. Except my stomach protesting half the ride it wasn’t as brutal as I expected, only long, very long. I left Litomerice before 8:00, met with Vojta around 3 hours in, we had a quick stop for a large bowl of pasta with tune and sauce and a coffee at Plzen at around 13:00 and we arrived at Doubravka at 19:30.

And I migrated this website to Cloudflare using their new Cloudflare Pages service. Netlify was fine but now I can have everything under one roof and Cloudflare has also some other cool services I can’t wait to try.

Reading

Importance of saving early from Bogleheads - no matter what for are you saving the power of compound interest will help you to reach your savings goal, even with low expected returns
The Trillion Dollar Lawsuit - about the 2017 Bitcoin Bubble and market manipulation.
Where Did the Other Dollar Go, Jeff?
The real reason to end the death penalty and this comment on HN that is quite on point:

This is the obvious reason, but of course there are many more: executions are quite expensive, they don’t seem to actually deter crime, they’re fundamentally pessimistic (“this person will never be useful to society”). Plus, they’re kind of unnecessarily cruel: if we wanted to execute people painlessly we could just pump a room full of nitrogen and let the person drift off into unconsciousness and death relatively quickly and silently. But for whatever reason we don’t do this, instead opting for spectacles of shooting the person or zapping them or injecting slow paralytics into their veins. My personal guess is that people like to watch for some sort of catharsis which a silent death doesn’t give them, but of course I’m not necessarily in a position to judge this well.

Luckily, capital punishment has been abolished in 1990 in Czech republic.

Watching

Shadow and Bone - not as dark as I hoped for it to be, nice filler between Witcher seasons nevertheless.
Draw with Tomm Moore - lesson by one of the animators behind Wolfwalkers

Listening

Coffee

Nothing new in April. Will order something good this month.

Stats

Net Worth: €9696.09 (+€1721.88)

Running: 5.4 hours, 71.45 km, 7 runs

Cycling: 48.82 hours, 1275.37 km, 16804 m ↑, 17 rides

Swimming: 0 hours, 0 km, 0 swims

Activity Totals: 66.2 hours, 1529.04 km, 35 activities

Growth

matousdzivjak@gmail.com (Matouš Dzivjak) — Fri, 16 Apr 2021 00:00:00 +0000

Growth is a book by Vaclav Smil that examines the ways in which human societies have grown and developed over time, from micro-organisms to modern societies. The book is a comprehensive and in-depth exploration of the various factors that have contributed to human growth, including technological innovation, economic development, and population growth. Growth provides deep insight into the patterns of growth that can be found in anything that we observe and where these patterns break.

Throughout the book, Smil uses a wide range of historical and contemporary examples to illustrate the complex and interrelated processes that have driven human growth. He also examines the various challenges and obstacles that have hindered growth, such as resource constraints, environmental degradation, and social inequality.

Despite the book’s length and technical nature, it is written in an engaging and accessible style that makes it a fascinating and informative read. Still, I did not finish the entire book and hope to come back to it one day.

Spotify TUI

matousdzivjak@gmail.com (Matouš Dzivjak) — Fri, 16 Apr 2021 00:00:00 +0000

Spotify TUI is spotify client for the terminal written it rust. It provides all the features of the desktop spotify app within the comfort of your terminal.

Installation

There are two installation options for Spotify TUI. Either you install just the TUI but in order to play music you will have to either the desktop app running, website open, or some device connected. Second option is to install it alongside spotifyd which is background deamon that acts as a spotify connected device and allows you to play music on you desktop/laptop without anything other running.

Setup spotifyd

spotifyd is an open source Spotify client running as a UNIX daemon. In other words, spotifyd is a deamon that acts as a spotify client allowing you to play music on your device without the need of having the spotify desktop app running or the spotify web app open.

spotifyd can be easily installed using brew: brew install spotifyd.¹

There are some additional tweaks that need to be done on MacOS before the deamon can run. First, make sure that you have directory for the spotifyd config file:

mkdir -p ~/.config/spotifyd

Next, create following config file modifying your username as needed:

echo "[global]
username = "your_username@example.com"
use_keyring = true
backend = "rodio"
" > ~/.config/spotifyd/spotifyd.conf

If you want to learn more about the configuration options see the full reference.

The configuration above takes advantage of the MacOS Keychain to store the password. To add the password to the kaychain, run:

security add-generic-password -s spotifyd -D rust-keyring -a your_username@example.com -w

This will prompt you for the password for you spotify account. After this step you are all set and ready. Just start up the deamon:

brew services start spotifyd

Setup Spotify TUI

Next step is to install and configure the Spotify TUI. First install it using:

brew install spotify-tui

Next, connect it to the Spotify’s API. This involves a few simple steps that will be displayd when you first run the tui (spt). They go as follows:

Go to the Spotify dashboard
Click Create an app, the name and description doesn’t matter, you can for example use Spotify TUI
Now click Edit Settings
Add http://localhost:8888/callback to the Redirect URIs
Scroll down and click Save
You are now ready to authenticate with Spotify!
Go back to the terminal
Run spt
Enter your Client ID
Enter your Client Secret
Press enter to confirm the default port (8888) or enter a custom port
You will be redirected to an official Spotify webpage to ask you for permissions.
After accepting the permissions, you’ll be redirected to localhost. If all goes well, the redirect URL will be parsed automatically and now you’re done. If the local webserver fails for some reason you’ll be redirected to a blank webpage that might say something like “Connection Refused” since no server is running. Regardless, copy the URL and paste into the prompt in the terminal.

🎉 that’s it, you are set and done. Now you can sit back, relax to some chill music and watch your colleagues gaze in envy.

By the way, if you don’t want to keep the spotifyd running in background you can alias spt to this:

alias spt="brew services start spotifyd && spt && brew services stop spotifyd"

https://spotifyd.github.io/spotifyd/installation/MacOS.html ↩︎

Preventing path traversal in Go

matousdzivjak@gmail.com (Matouš Dzivjak) — Fri, 02 Apr 2021 00:00:00 +0000

New project surfaced in our company, unoriginally called IAP GCS proxy. As the name suggests, it is a small Go proxy that provides IAP restricted access to Google Cloud Storage buckets.

Within minutes one very interesting comment by Martin Bajanik, a senior application security engineer, appeared in the slack thread that caught my attention:

This might allow path traversal from the outside to traverse to a different bucket, which might be a problem if we ever reuse the same SA on two different buckets

talking about this piece of code:

upstreamUrl, err := url.Parse(fmt.Sprintf("https://storage.googleapis.com/%s%s", gp.GCSBucket, req.Path))

Don’t trust the user

So, what’s the issue with this line? Assume that someone send the following request to the IAP GCS proxy:

curl https://gcs-iap-proxy.company.com/../another_bucket/super_important_file.txt"

with the code above this results into the upstream url being https://storage.googleapis.com/target_bucket/../another_bucket/super_important_file.txt effectively allowing path traversal to other buckets in the google cloud storage.

Escaped path

Initial attempt to solve this was using request.EscapedPath() instead of request.Path.

- upstreamUrl, err := url.Parse(fmt.Sprintf("https://storage.googleapis.com/%s%s", gp.GCSBucket, req.Path))
+ upstreamUrl, err := url.Parse(fmt.Sprintf("https://storage.googleapis.com/%s%s", gp.GCSBucket, req.EscapedPath()))

This would work, but would result into weird requests being send upstream, such as https://storage.googleapis.com/target_bucket/..%2another_bucket/super_important_file.txt and left me wondering, whether there’s a more elegant solution to the problem at hand.

Secure join

After a quick search I landed on this issue at github.com/golang/go: proposal: path/filepath: addition of SecureJoin helper that suggests new filepath function SecureJoin that would prevent path traversal in filepath.Join. Sadly, but rightful, the issue was closed as there wasn’t compelling reason to include this into the standard library. Some people suggested using securejoin.SecureJoin but as one of the great Go proverbs goes, A little copying is better than a little dependency.¹. For sure, there must be a way to solve this using the tools at hand.

Path clean

Further googling landed me at ServeMux and a path traversal vulnerability article by Ilya Glotov. There, the proposed solution is lean and clean:

cleanPath := filepath.FromSlash(path.Clean("/"+strings.Trim(req.URL.Path, "/")))

path.Clean cleans the path getting rid of any parent directory references (../), that is, if the path is absolute which is a very important gotcha. Of course, it makes sense, there’s no way to clean path such as a/../../b since the parent directory could be anything and we don’t know the file system hierarchy. On the other hand, path such as /a/../../b can be safely cleaned. First ../ sequence lends us in the root directory, the second one is basically ineffective as the root directory doesn’t have parent directory and the final /b references a directory within the root.

In the proposed solution this is solved by forcing the request path to always be absolute by prefixing it with /. Calling path.Clean than cleans the path from any parent directory references which in turn prevents the path traversal on the upstream.

One could end here and consider the issue done and solved. What I didn’t like about the solution though is the call to strings.Trim and the string concatenation. Surely we can do without it.

The final solution

As it turns out, the whole problem of request path based path traversal on the upstream can be solved using single standard library function call.

cleanPath := path.Join("/", req.URL.Path)

How so? path.Join not only joins the path parts in the variadic arguments list but also calls path.Clean on the result. Thus the path.Join("/", req.URL.Path) in one swift call both prefixes the request path with /, ensuring that the path is absolute and will be properly cleaned, and also calls path.Clean on the result.

Since this behaviour of path.Join might not be fully intuitive, it is a good idea to add a comment before the call stating that we rely upon the internal path.Clean call. And if that isn’t sufficient ensurement that the call won’t be removed some time in the future, one can go as far as adding an explicit path.Clean call on the result: path.Clean(path.Join("/", req.URL.Path))

That’s it for today. I hope you find this useful in case you are solving an issue of similar nature.

https://go-proverbs.github.io/ ↩︎

March

matousdzivjak@gmail.com (Matouš Dzivjak) — Thu, 01 Apr 2021 00:00:00 +0000

This month I did something I should have done a long time ago. I started learning Kubernetes. I already read a little bit about the internals and spend a lot of time reading documentation for Nomad by Hashicorp, younger, simpler sibling of kubernetes. Kubernetes is a whole another level of monster though.

I will be leaving my current job at Kiwi.com and joining SumUp in June. Most likely remotely at the beginning but I plan to move to Berlin as soon as the situation permits. This was a huge decision and not an easy one to make. I like Kiwi.com, the team, the people, the job. The thing is, there most likely won’t be a better time than now and this is an opportunity I would be a fool not to take.

Mallorca

Not very often, especially in these times, you get the opportunity to set foot (or a wheel) abroad. So when I was approached by a friend with the offer of flying to Mallorca for 10 day cycling trip I accepted it without much hesitation. To be honest, I was quite nervous because my road cycling experience until than consisted of around 400km in 3 months. It didn’t help much either that I would be in a company of experienced riders with track record of years with over 10,000km and multiple wins on Czech as well as foreign races.

It goes without saying that the trip was intensive and demanding but to my surprise my legs held quite well. In the 10 days on the scenic island of Mallorca we rode 1097.86 km with average speed well above 30 km/h and grand total of 12,171 vertical meters. I saw the most remarkable sights such as Formentor and the bay of Sa Calobra (this one still hurts).

Overall, and in simple terms, I loved it. In a company of great people the suffer fest turned into one of the best vacation I ever had and I hope there will be more in the future.

The act of note taking

Robin Cussol, colleague of mine, has this well written and highly informative blog. In his 2020 year review he mentions a habit that I wanted to implement for quite some time: note taking.

In the online world we are surrounded with vast amount of information on all the possible subjects. News, social media, pictures, even videos are all build to be consumed in great quantities, fast, and without many thoughts. Yet, we prosper the most by diving deep into the things that we enjoy or that we want to learn.

Taking notes forces you to slow down. To better consider what you spent your time on. And for me most importantly there’s actually something left behind instead of me forgetting everything in matter of hours. Partially, I take my notes here, on this blog. Either in the form of book wrap-ups and reviews or in the form of short blog posts and monthly look-backs. I also have plenty of stuff written in Notion where I did a large cleanup recently and decided to delete as many links as possible. Instead, I tried to write short TL;DR of what I learned from the article and I plan to keep this approach further. Would be nice to do the same thing with the hundreds of opened tabs in my mobile web browser but that will take a few days so maybe another time.

Reading

Clean Architecture with GO. Even as my knowledge of Go ecosystem grows, I am yet to find out, what the best application structure is for clean and maintainable APIs. For example the MVC pattern isn’t really applicable in Go, rather structures similar to api <-> service <-> storage can be often seen, but those sometimes fall short of the needs as well. This article provides a nice take on alternative approach with schema controller -> interactor -> presenter where controller encapsulates the request logic, interactor handles the internal stuff you would normally find in the service and storage layer and presenter handles the transformation of the application models back into response returned to the user.
The Pirate Problem, what could be hard about five pirates dividing a treasure.
Nomad is workload orchestrator developed by Hashicorp. It’s wonderful piece of software that I started to dig into to better understand internal working of workload orchestrators and schedulers (think kubernetes).
r/WhiteHouseBets by Alex Danco, on GME, Reddit, reflexivity, and how internet enables crowds of people to focus their attention onto singular thing.
A Sea Story by William Langewiesche. After quite some time I found myself on an airport quickly looking for some read into the airplane. And where else to look for than in the archives of William Langewiesche’s. This time, another disaster horror story from 1994 when 850 people lost their lives on board luxurious ferry on the Baltic sea.
Tracing Paper by Mitch Anzuoni. That your digital footprint is easily trackable is now a fact almost taken for granted but who would have assumed that printed documents could be tracked too?
Inside a viral website by Tom. Ever Given container ship blocked the Suez canal for just over 6 days which had not only impact on large portion of the world’s trade but also the world’s meme scene. One of the greatest memes being istheshipstillstuck.com. This article talks about running the viral meme website that attracted large amount of traffic of the course of the 6 days and goes into details of how the author tried to monetize it.

Watching

Authentication as a Microservice, Brian Pontarelli’s take on Jason Web Tokens.

Listening

Charli XCX, supposedly this is called Hyperpop, and I like it.
Verboten Berlin, electronic/dance music.

Coffee

Columbia Doris María by Zoban
Honduras Caballeros Zoban

Stats

Net Worth: €8025.19 (+€297.83)

Running: 14.93 hours, 201.09 km, 14 runs

Cycling: 46.98 hours, 1374.48 km, 15474 m ↑, 17 rides

Swimming: 0 hours, 0 km, 0 swims

Activity Totals: 67.42 hours, 1594.03 km, 37 activities

February

matousdzivjak@gmail.com (Matouš Dzivjak) — Tue, 02 Mar 2021 00:00:00 +0000

I was there, on r/wsb, during the $GME boom. For two weeks my Reddit feed didn’t contain anything else than GME memes, calls to arms, and too many posts of people betting their life saving on Robinhood.

Little rant ahead…

Czech Republic is breaking all records regarding Covid-19. Here we are, small, insignificant, middle-European country ranking top in at least something except beer consumption. And while many countries are slowly returning to regular life, Czech republic is in despair taking further measures to put a stop to the hyperbolically growing number of cases. We are going into the March with the country being locked up to individual districts. Vaccination is super slow and would be probably even slower haven’t we received dontaions from neighboring countries. And last but not least the only thing left after Chytrá karanténa, E-Rouška, Polní nemocnice, PES (Protiepidemický systém), and other government projects that should have helped with the situation is the largest budget deficit up to date.

Reading

This month was in the spirit of coding and programming. I read the whole documentation of Hashicorp Waypoint. It’s still pretty young but very interesting technology that aims to “provide a modern work flow to build, deploy, and release across platforms”. As with anything else by Hashicorp it is just wonderful piece of software. Waypoint is in it’s infancy and under heavy development but it will be interesting product to watch.

As I spend a lot of time working I wasn’t quite in the mood for books, on the other hand I found a couple of interesting articles. Here are the ones that I enjoyed:

How GMOs can save civilization (and probably already have). I was searching for the ingredients used in the vegan alternatives to meat and this article popped-up. The subject of GMO is also mentioned in Growth by Vaclav Smil and both of these sources seems to pretty much agree on one thing: If we want to feed the whole planet GMO is the solution.
Maersk, me & notPetya by Gavin Ashton. When world largest shipping company and a malware meet.
You Can’t Kill the Bloomberg Terminal. But If You Were Going to Try, Here’s How.
Why Forgiving Someone Else Is Really About You
Invert, always, invert
dorking (how to find anything on the Internet)
Robinhood and How to Lose Money
How I cut GTA Online loading times by 70%

Listening

The Kid Laroi. It’s not everyday you listen to the same artist as your 15 years old sister.
Orphée by Jóhann Jóhannsson, last album of Icelandic composer who worked on original scores of many of my favorite films.
Hello 2021: Maduk on repeat.

Coffee

Ethiopia - Aricha by Zrno44, friend of a friend started a roastery and offered samples from the very first batch. Not as acidic as I like but for a first batch? Job well done.
Ethiopia - Koke by Nordbeans. By Nordbeans standards nothing overwhelming.

Based on recent experience, Ethiophia is not quite my cup of coffee (all puns intended).

Stats

Net Worth: €7727.36 (+€1441.02)

Running: 17.16 hours, 220.81 km, 17 runs

Cycling: 4.06 hours, 115.91 km, 1231 m ↑, 2 rides

Swimming: 0 hours, 0 km, 0 swims

Activity Totals: 40.3 hours, 444.76 km, 27 activities

January

matousdzivjak@gmail.com (Matouš Dzivjak) — Mon, 01 Feb 2021 00:00:00 +0000

The start of January was hectic. Several school projects that I left hanging needed to be done in a short period of time. I spent whole first weekend of January catching up Blockchain and TLS homeworks for Cybersecurity labs and a few afternoons drawing scratches for the Art class. Anyway, hell or high water I still squeezed in 2 weeks of ski touring in Krkonoše in terrific conditions. In the typical Krkonoše manner the ridges were cold and windy but a few meters lower we had better conditions than in the Switzerland. Tone of powder, great visibility and only a few other enthusiast cutting their way up for the minute of glory on the way down.

The 2021 is going well so far. I am running 10k per day so far, writing slightly less than desired, skiing more than I hoped for, being considerate of my spendings, and still enjoying every day like there’s no other.

Although not a formal mental-health diagnosis, duck syndrome has mostly been described in college or graduate students and refers to the situation in which the sufferer looks completely calm on a superficial level while in reality they are frantically trying to keep up with the demands of their life. Duck syndrome often indicates that the person experiencing it is suffering from clinical depression, anxiety, or another mental illness. Duck syndrome and a culture of misery

Reading

How to Do Nothing by Jenny Odell, I like the writing slightly more with every page that I read. Certain ideas in the book are too abstract for me to grasp but other concepts seem to resonate with me. For example the phenomena of Context Collapse. Context collapse describes how our internet self is usually the lowest denominator because we are sharing with broad spectrum of people and want to please everyone. Example in the book mentioned following situation: imagine that you return from lengthy vacation abroad in an exotic country and want to tell someone. You would tell the adventurous and humorous version to your friends, slightly less inappropriate version to you parents, and informative and shorter version to your grandparents. Now with our social media reaching all of these groups we are constantly thinking up things that would go over well with all of them instead of saying the right things to the right people. How to Do Nothing presents more such ideas to think about.
The Three-Body Problem by Liu Cixin, brilliant fictional book with deep philosophical and scientific reach that definitely earned its place on the list of my most favorite books.
Growth by Vaclav Smil, had this book in queue for quite some time, now it’s time for it to live up to the expectations.
Chemistry of Cast Iron Seasoning: A Science-Based How-To tl;dr: start with linseed oil, rub the pan, bake, rinse and repeat.
Cameras and Lenses one great article for in depth understanding of cameras and lenses. Also the best interactive examples in an article I have ever seen.

Listening

Liquicity release bunch of DJ sets in a series called Hello 2021. Polygon and Maduk are currently my favorites and I have them on repeat every run.

Coffee

BIO Ethiopia Yirgacheffe Koke by mamacoffee. A Christmas gift, perfect one nevertheless. Best coffee in a very long time, acidic and rich in flavor.
Nikaragua Salomón Chavarría by mamacoffee. Another Christmas gift.

Stats

Net Worth: €6286.35 (+€1500.13)

Running: 25.59 hours, 329.3 km, 22 runs

Cycling: 0 hours, 0 km, 0 m ↑, 0 rides

Swimming: 0.1 hours, 73 km, 2 swims

Activity Totals: 44.03 hours, 498.46 km, 33 activities

The Three-Body Problem

matousdzivjak@gmail.com (Matouš Dzivjak) — Sat, 23 Jan 2021 00:00:00 +0000

The Three-Body Problem hit the right spot for me and placed itself on the list of finished in a day or so books. I attribute that mostly to the book being more on the Sci side than the Fi (whatever that means). The scientific concepts in the book were mostly familiar to me and played nicely together. Some of the character arcs seemed a little bit far fetched and flat but the scientific side of the book balanced that out.

The book gradually builds up the pace over first 100 pages and than turns into one thrilling rollercoaster with interesting plot-twists that keep you on the edge of the seat gasping for yet another page. Cixin Liu was able to combine Chinese Cultural Revolution¹, The Three-Body Problem², Particle Physics³, Newton’s laws of motion⁴, von Neumann Architecture⁵, and plenty other topics into one brilliant masterpiece this book is.

I am looking forward reading the next two books in the series and will unreservedly recommend The Three-Body Problem to anyone looking for conceptual, intelligent, fictional book.

Backcountry skiing in Switzerland 2020

matousdzivjak@gmail.com (Matouš Dzivjak) — Wed, 20 Jan 2021 00:00:00 +0000

Here’s a little, unfinished take on our latest skitouring trip to Switzerland. See the attached Strava activities for more photos and full route.

With the scary vision of after-christmas overeating we packed our packs in the evening of 24th December and soon after, in the morning hours of 25th, we left for the Switzerland.

Flüela Wisshorn

After a cold night in a car (and by cold I mean really cold) we had a slow breakfast, cup of aeropress coffee, and we set off around 9:00. To our great horror after about an hour later we realized that we left all snacks in the car. With a vision of already ruined day we slowly broke our trail through the deep, fresh snow. The effort was grueling. Slowly we diverged from our originally planned route and later on had a lot of trouble getting back between steep slopes, giant boulders, and high snowdrifts.

The day was slowly passing by, and it didn’t take long for us to realize that we are far behind the schedule. Still, we made our way until we were mere 100 vertical meters from the Flüela Wisshorn peek. There we reasonably decided to turn around. The sun was slowly setting toward the horizon and we were already tired, bad snow condition didn’t help either.

Downhill was fun, except a few little slabs that slowly rolled away here and there… We enjoyed our 5 minutes of fame before the gradient evened out and we had to walk for a little bit more. The rest of the downhill was zigzagging between stones deep hidden under the powder cover. The skis suffered a couple of hits but nothing horrific.

St. Antönien

Fadeuer

Büelenhorn

Sulzfluh

Piz Dal Sasc

Tschima da Flix

How to Do Nothing

matousdzivjak@gmail.com (Matouš Dzivjak) — Tue, 19 Jan 2021 00:00:00 +0000

Not really a guide to Doing Nothing or Resisting the Attention Economy as a matter of fact but interesting book nevertheless.

How to Do Nothing is well written and thoughtfull about philosophical and seemingly abstract concepts of the self, attention, bioregionalism, and community. More than a guide the book poses as an essay on what we are missing when social media grasps our attention, and whether our idea of “usefulness” is the right one. Should we really consider time and attention to be a commodity we can exchange for salary? And are we expressing ourselves honestly when we are limited by 280 characters and want to please each and every follower?

There is really no summary to this book as it flows from one concept to another with sometimes hard-to-grasp diversions to art, birds and nature. Would I recommend the book? I don’t know. It wasn’t my cup of tea yet I somehow unintentionally finished the book and learned to like it on the way.

December

matousdzivjak@gmail.com (Matouš Dzivjak) — Fri, 01 Jan 2021 00:00:00 +0000

Switzerland

Reading

Not much. I am still slowly reading Capital in the Twenty-First Century by Thomas Piketty, and by slowly reading I mean I haven’t touch it for a month or so. Other book that is taking me quite some time is How to Do Nothing by Jenny Odell, it’s a nice read about the modern obsession about productivity, FOMO and more. I like the ideas in the book but they are all hidden somewhere inbetween paragraphs of unnecessary philosophical thoughts that make for a slower read (as ironaical as it is, I guess it might be intentional, you can’t just effectively speed throughout the book).

The Shipbreakers, whenever in need of a great thrilling read, William Langewiesche is there to cover. This time with a story from the biggest ship graveyard in the world.

Coffee

This month I had:

Etiopie – Sahille by Zoban, nicely aciding but flat in flavor, not great, not terrible (judging by Zobans standards, so still a superb coffee)
Šumava (Costa Rica) by Doubleshot, drinked in the evenings in Switzerland Alps, I had only a few cups in field conditions but liked it a lot. Might consider trying more beans by Doubleshot in the future.
Burundi by Kavaprodej, this is the go to “I want coffee but don’t care that much about the taste so I might as well drink something cheaper” brand. It has mild-ish taste but great value for money.

2020 Review

matousdzivjak@gmail.com (Matouš Dzivjak) — Mon, 28 Dec 2020 00:00:00 +0000

⚠️ This article is meant mainly for future me. It’s not meant to be a brag-fest, rather a summary I can come back to later.

2020, my oh my, what a year.

Since the history of 2020 most likely won’t perish in time I won’t go into much detail here. Let’s just say that post-corona adjustments were quite significant. More about that later…

Since the start of the year in chronological order:

With more time on my hands than ever I went all-in on sports. Detailed stats are below but to summarise it I:
- ran more than ever and broke my personal bests with 5k at 19:51, 10k at 39:47, half-marathon at 1:27:36, and marathon at 3:25:15 (I burned through 3 pairs of running shoes 💸).
- cycled more than ever, did my first 200km ride, and bought a road bike 💸.
- completed half-Ironman in 5:24:56 (1.9k swim at 43:43, 90k bike ride at 2:52:00 and 21.1k run at 1:41:30).¹
- there’s probably more but I already forgot.
I didn’t have any diving holidays 😔.
I spent a lot of time with friends, I feel like that’s somethings I neglected lately.

And in no-particular order:

first time skitouring, the gear cost me a fortune but the powder rides are worth it.
started this website.
finished a bunch of books after a one-year reading break.
tracked my finances for the whole year.
tracked my food for 3 months.
went semi-vegan. Now I eat mostly plant-based food but still have a meat or animal product from time to time. I love how easy the diet is to digest; I can have lunch at 13:00 and go for a run at 14:00 and my stomach won’t turn upside down.
did my first pull-up (also 3 in a row). It’s all about the technique.
cooked almost every day for myself and my siblings and learned a bunch of new recipes and cooking tricks.

I also did a great clean up in my life. I deleted facebook and never looked back. The only thing that I miss are the various small marketplace groups and notifications about events. I gave away or sold a lot of things, clothing, gifts I came by over the years that never left their packaging, and old electronics that were just lying around unused. The minimalistic approach to life brings peace to the soul. I got rid of all my non-plain t-shirts and trousers and would like to bring it further this year and maybe even get to one or two colors only. The less decisions one has to make the better.

Bread was the signature food of 2020. I couldn’t be more mainstream than baking sourdough bread during the lock down. I kept baking though and still enjoy it. It still ceases to amaze me how different results can one get depending on the process and ratios of water and flour. And I am far from good at baking bread. I think I didn’t get consistent results even once and I still have no idea why things go wrong when they go wrong which I think is pretty important skill to have to get better.

Stats

I started collecting statistics about a lot of things I do. Mostly finances and sports, but for a few months I also logged every meal I ate. I do that mostly for two reasons. Firstly, I can improve. Be it the way I handle finances or the way I train. Secondly, I enjoy it. So without further ado here’s a brief summary of statistics I was able to collect over the course of 2020.

Sports

This year (since the end of April when I bought my Garmins and started tracking everything on Strava) I did 141 runs, totaling 1628 km in 127.5 hours. Probably more than in all other years together. The same applies for cycling as well where I finished with 66 rides for total of 3604 km and 55097 m elevation gain in 169 hours. My swimming performance was poor, partly due to the corona restrictions (swimming pools were closed) and partly because I still don’t like swimming as much as cycling or running. I did 20 swims with total distance around 30km (the figures are estimates because I used swimming tracking to track the cold bathing sessions). In the end, I squeezed 350 activities into approximately 250 days; for total of 435 hours and 139401 kCal (maybe the only reason I am not overweight yet).

Overall, I consider all of that quite an achievement. I was more active than in all my university years combined. I mostly attribute that to not being in a relationship after 5 years, i.e. no restrictions on what I spend my time on. Other factor is, that being active makes me happy and I feel guilty if I don’t do at least some activity in a day.

I hope to keep the pace even the next year and would love to pump those numbers up a little bit more. The goal is to run 1875km (5km a day), ride 3650 km (10km a day) and swim 365km (1km a day). Those targets are quite low because I don’t want to stress myself and I will go for more either way. I would also love to run the sub-3 marathon and finish a full Ironman race.

Plan profiles of all my activities plotted as small multiples. Spot the regular running route to Třeboutice.

Elevation profiles for my activities.

All activities plotted in a plan, cut out around Litoměřice (the darkest spot).

Inspired by https://marcusvolz.com/strava/.

Finances

2020 was year of great sporting expenses. 48% of my expenses went to sporting and sporting goods. Of that, cycling accounts for 1/3 (mostly because I bought new road bike), 1/4 went into ski touring gear and 1/6 into shooting (license and gun). I hope the new equipment will last for at least a little bit and the sport with consume much less of my income next year.

Vacation expenses were super low because of corona, 13.379 Kč in total. While I don’t have numbers from previous years I assume this is around 25% compared to what it was. I also spent 18.810 Kč on coffee 😱, out of that 8.500 Kč at Káva s Párou, basically my co-working space since August. I managed to put aside 130.000 Kč, not great, not terrible. It’s a lot more than the previous years but far less in the income percentage than I wold like. This is definitely the biggest goal for next year - safe more.

2020

Overall, 2020 was a great year. I was active. I had fun. And most importantly, I was happy. Doing so many sports and activities brings a lot of joy and variety into what would otherwise be very monotonic life and I want to keep that up. Sometimes it gets lonely but there are always friend and family to step in and after all, no relationship is better than relationship that doesn’t fit anyones needs. If even this year was great after all I can’t wait to see what’s coming up.

https://www.czechtriseries.cz/results/track/12975?embedded=False&highlightRacerId=141977 ↩︎

November

matousdzivjak@gmail.com (Matouš Dzivjak) — Tue, 01 Dec 2020 00:00:00 +0000

This month I… didn’t write the Lately post. I didn’t find the right opportunity and mood to do so so I am writing this with one month delay. Out of the window goes the regular writing while the memories are fresh.

I spent a night in -5 degress, wind, and snowy weather outside on the Holubník hill in the Jizerské Hory. We went there for hike with Bára and her friends, and Floki, cheerful, energetic collie. The talks about buying a dog in our family continue but the concerns about who will take care of the dog when the kids leave and would we have enough time for it are still overweighting the rest.

I watched Kilian Jornet try and fail world record for 24 hour run which brought me to question: What is the best time to start 24h attempt? (for the record, they started around 10:00 or 11:00). I couldn’t find the answer anywhere.

We (I and my sister) already had almost all the gifts for christmas by the end of the month. This makes for a chill and stress-less December (not that I would be stressed anyway but I am definitely happy that we have this behind us sooner than later).

I most likely did also some other stuff but as already mentioned, I am getting back to this post with a delay so I no longer remeber.

Reading

The Hitchhiker’s Guide to Galaxy
Typeface Mechanics: 001
Why We Can’t Solve Big Problems by Jason Pontin
In the late 1990s, venture portfolios began to reflect a different sort of future … Venture investing shifted away from funding transformational companies and toward companies that solved incremental problems or even fake problems … VC has ceased to be the funder of the future, and instead become a funder of features, widgets, irrelevances. What Happened to the Future? by Bruce Gibney
Doordash and Pizza Arbitrage - closely related to the previous article
The Founders Fund

The Hitchhiker's Guide to the Galaxy

matousdzivjak@gmail.com (Matouš Dzivjak) — Fri, 27 Nov 2020 00:00:00 +0000

I am pretty late to the party with this book but as the saying goes; Better late, than never. The Hitchhiker’s Guide to the Galaxy is a delightful book, brilliant in both its witty humour and unique style. Fiction was a welcomed break from all the demanding books I read lately, and I have a strong feeling I will include more fiction books into my reading queue.

For a moment, nothing happened.
Then, after a second or so, nothing continued to happen.

As a side note, my plans of scrutinizing this book thoroughly bit by bit went out of the window after a few pages, and I devoured it in less than a day.

How To Lie With Statistics

matousdzivjak@gmail.com (Matouš Dzivjak) — Thu, 26 Nov 2020 00:00:00 +0000

Summary

sample with a built-in bias: What will the average salary be if you ask Cambrdigegraduates?
well-chosen average (mean x median x _mode): Average person has less than 2 arms
little sample(s): Having enough small samples you can select the one, that suits you the best.
nice wording of practically nothing: “Camels are better than Marlboro”, yet they are both bad.
graphs (changing the scale or not labeling the graph at all):

XKCD #833 by Randall Munroe

one-dimensional picture: You can make the difference look greater by increasing the dimensionality of the graph.
semi-attached/irrelevant figure: New Anticovid™ gel kills 13943 germs in 12 seconds.
post-hoc:

XKCD #552 by Randall Munroe

Info

Title: How to Lie with Statistics
Author: Darrell Huff
ISBN10: 0393310728
ISBN13: 9780393310726

Capital in the Twenty-First Century

matousdzivjak@gmail.com (Matouš Dzivjak) — Wed, 04 Nov 2020 00:00:00 +0000

Key Takeaways

Inequality grows if rate of return on capital is greater than the economic growth. That is, when the average returns on capital (such as dividends, interest, rates, and profit) are higher than the economic growth (growth of society’s income/output) people with more capital tend to cumulate more wealth, increasing their income even more. This in turn accelerates the growth of the gap between wealthy and poor.

Sapiens: A Brief History of Humankind

matousdzivjak@gmail.com (Matouš Dzivjak) — Tue, 03 Nov 2020 00:00:00 +0000

Modern society is shaped by capitalism and consumerism. Expensive fashion, travel and social media dictate our lives without us betting an eye. How have we got to this point though? And more importantly, why have we got to this point? These questions and many more are answered in Sapiens: A Brief History of Humankind.

In Sapiens Harari divides the history of human kind into three distinctive important eras. Our history began with the Cognitive Revolution (70,000 BCE). Cognitive revolution happened when we developed imagination. Imagination allowed us to dominate the world through the ability to believe in imaginary things such as gods, money, nations, laws, and more. All large-scale cooperative human systems found their foundation in the cognitive capacity for fiction. Be it trade networks, religions or political systems. All these systems are purely abstract yet enabled us to cooperate on unprecedented scale, thus overpowering all other living species. For example money, the powerhouse of economies and trade, is a system of mutual trust. Money have their value simply because we (collectively) believe in their value. The time when value of money was backend by the actual precious metals is long gone, and even then what allowed money to exist is that we trusted that we will be able to exchange money for goods because others have the same believes and will be willing to accept money as a form of a payment.

With the money we are getting ahead of ourselves though. It was only in 3000 BC in Mesopotamia when the first commodity money - shekel - was introduced. The first result of the abstract thinking was the ability to build larger groups. The large scale human cooperation in the form of archaic tribes, medieval kingdoms or modern states is rooted in common myths, existing purely in our collective imagination. None of these things exist outside the stories that people invent and tell each other.

The second era began with the Agricultural Revolution in 10,000 BCE when first Sapiens settled and learned to co-evolve species like cows and wheat. With agricultural revolution also came large population growth. Large plains that were once able to feed single wondering tribe were now thanks to agriculture able to feed many times more. The key claim regarding the agricultural revolution though is that it made the lives of most individuals and animals alike worse. Daily lives became less varied, our diet shrunk to a few crops and meat of domesticated animals, and the permanent settlements brought diseases and other problems that we were able to avoid thus far. All of this also required us to work more and harder. Why did the agricultural revolution happen even at this cost? Frankly, we are not sure. What we know is, that it wasn’t possible to go back to our hunter-gatherer style of live once the revolution began.

The Scientific Revolution began the last era. Scientific revolution was founded on change in European though, whereby elites first time in the history became willing to admit ignorance and try to remedy. With our newly gained power of saying “we don’t know” and “we were wrong” we started to discover more of the world and making first scientific breakthroughs. Seeing the advancements that we are able to achieve gained science more trust which in turn brought more money, which in turn brought more scientific advancements that allowed us to enrich ourselves. This started the self-stimulating cycle of power, resources, and research. More research brings more power, more power means more resources, and the more resources are available the more we can invest back into research.

The idea of progress also funded the modern economy. Whoever believes in progress believes that our technological inventions and organisational development can increase the total sum of human wealth, production and trade. Progress broke our belief that economy is zero-sum game where gains of one are losses of others. Once this dogma has been broken and people started to believe in better future new doors opened. People agreed to represent imaginary goods - things that don’t yet exist - with what is called credit. Credit enabled us to build the present at the expense of future. All this is funded on the assumption that our future resources are more abundant than our present resources. Baker could come to a bank to borrow money to open new bakery. Bank would be willing to lend the money believing that the baker will be able to generate income in foreseeable future to pay his dept. All of this was and is possible only thanks to our collective believe in better future and growth of overall wealth.

Many more ideas and phenomenas are presented in the book, too many of them to list them all. I hope that the previous paragraphs are enough to give you an overall idea of what to except. Overall, Sapiens: A Brief History of Humankind is a fantastic book that puts so many things that we take for granted into their true perspective. The book also made me realize that the history ain’t all sunshine and rainbows. Mistakes were and still are made. Because of our greed many species are extinct or live miserable lives to end up on our plates. And are we even happier and better of than we were 70,000 years ago? In the essence of scientific revolution it is ok to say that we don’t know. Let’s just hope that we are building better future not only for us but also for other species.

October

matousdzivjak@gmail.com (Matouš Dzivjak) — Sun, 01 Nov 2020 00:00:00 +0000

This is the first entry in the Lately series.

Lately will be my monthly journal (no guarantees about the time frame). I think it could help me with the inability to write coherent pieces of text. Since it will be shorter - paragraph or two - and contain more topics I won’t deplete my limited vocabulary so quickly. Furthermore, keeping a journal might push me to appreciate more of the insignificant achievements and the joys of everyday life.

What will Lately look like? I enjoy Tom MacWright’s Recently blog posts and will take inspiration there. The format should be concise and to the point; starting with a quick overview of past month: things I have been doing, places I have been to and things I have been thinking, and other seemingly boring stuff. I might follow up with more in-depth paragraphs on individual interesting topics that I have lately come across. And, to wrap it up, a few words into the upcoming month will give everything a silver lining.

I still haven’t decided whether to write such entries gradually over the month or all later in retrospect. Right now I am more inclined to the former than to the later for the sake of capturing also the briefer ideas that cross my mind. Also, it might be easier to spit out the words over a time then to force myself to write all at once before I forgot what even was the last month about. Anyway, if this whole thing becomes a habit of mine I might try to A/B test both options and pick the one that suits me better.

October was quite a month. The Cisar Challange that we were registered for got canceled because of Covid concerns, so we ended up driving to Pilsner for some precious family time with the rest of Šťastňák family. Except the obvious - going for a jog - we have also seen the Collective; investigative documentary about the events following the fire at the club Colective that uncovered vast fraud in the Romanian health-care system.

Swimming pools closed forcing me to put on the neoprene and do my first swimming session in the Pískovna. Thankfully, cyanobacteria is not a big fan of cold temperatures, and the water had no longer rich green colour. We spent one more weekend with Šťastnáci on Doubravka, piling up wood for burning and cleaning a full room of artefacts from the beginning of 20th century. I also managed to do my first muscle up and later on also two in a row. A little, insignificant hurray to myself.

Other than that:

New member of the Why didn’t they force us to read this in high school instead? list is Sapiens by Yuval Noah Harari. I didn’t finish Harari’s 21 Lessons for the 21st Century about a year ago and was skeptical to start Sapiens. Nevertheless, it was one of the best reads of last year and definitely honourable member of top 10 list - if I had one. I encourage everyone to read it too.
I saw The Social Dilemma with the whole family. There’s not much new for computer engineers, but I enjoyed how easy to understand they made the topic of online privacy to non-technical folks. Doesn’t seem that anyone would walk away more concerned with his social media intake however, I hope that at least some parts of the movie will be remembered.
Still baking bread approximately every other day and getting better. I will try to write more elaborate article on that one day, until then: this guy knows what’s up. His recipes are easy to follow, and most importantly have reasoning behind the steps and ingredients.
First month of regularly cold bathing went well. On the 11th occasion it was 1 °C outside, the water had 9 °C, and heavy fog laid over the lake. Tell me more about perfect conditions.

The “PayPal Mafia” is a group of former PayPal employees and founders who have since founded and developed additional technology companies such as Tesla, Inc., LinkedIn, Palantir Technologies, SpaceX, Square, Slide, Kiva, YouTube, Yelp, and Yammer. Wikipedia

Nonviolent Communication

matousdzivjak@gmail.com (Matouš Dzivjak) — Sun, 18 Oct 2020 00:00:00 +0000

Nonviolent Communication by Marshall B. Rosenberg is an essential book on for anyone hoping to make life easier and more enjoyable for himself and people around. The book is plentiful in examples and summaries making it easy to adopt suggested methods and thoughts. Overall, the tone of the book is friendly and clear. The sections flow nicely one in to another slowly building upon the knowledge learned. Some examples in the book seem to be far-fetched hurting on the credibility of the book, despite that it still holds great value and provides great insight into what empathy really means.

Notes

Four components of NVC (Non-Violent Communication)

observations
feelings
needs
requests

We need to keep in mind that for MVC to work we should:

express honestly through the four components
receive empathically through the four components

In the end, the process looks like this:

the concrete actions that we observe that affect our well-being
how we feel in relation to what we observe
the needs, values, desires, etc. that create our feelings
the concrete actions we request in order to enrich our life

Communication that blocks compassion

moralistic judgements
making comparisons
denial of responsibility
thinking based on “who deserves what”

Observing without evaluating

Observing without evaluating is the highest form of human intelligence

It’s easier to provide a few examples:

“You are too generous” vs. “When I see you share your lunch with other I think you are being too generous”
“She’s ugly” vs. “Her looks don’t appeal to me”
“If you don’t eat healthy you will be fet” vs. “If you don’t eat healthy I fear you might become fet”

Identifying and expressing feelings

It’s easier to connect with one another if we can better express our feelings. For that we need larger vocabulary, good and bad won’t be enough. And we need to keep following things in mind:

distinguish between what we feel and what we thing others react or behave toward us.
distinguish feelings from thoughts.
- “I feel like a failure” vs. “I feel sad because my plans are failing”.
distinguish between what we feel and what we think we are
- “I feel inadequate as a waitress” vs. “I feel frustrated with myself as a waitress”

Taking responsibility for our feelings

Our feelings result from how we choose to receive what others say and do. E.g. what others say and do might be the stimulus four our feelings but never the cause.

We can deepen our awareness of our own responsibility for our feelings by connecting our feelings with our needs, e.g.: “I feel …, because I need…”.

distinguish between giving from the heart and being motivated by guilt

“Mommy and daddy are sad when you get poor grades at school”

The child will be motivated by guilt instead of giving from heart
judgement of others is alienated expression of our own unmet needs

e.g. we tend to judge other instead of expressing our own needs that make us feel certain way.
if we don’t value our needs others may not either

e.g. it is important to express our needs correctly, accompanied by our feelings. We can’t blame others when our needs are unmet if we don’t express them (obviously).

From emotional slavery to emotional liberation

Three stages:

emotional slavery - we believe ourselves resonsible for feelings of others. We think we must constantly strive to keep everyone happy and this overwhelms us.
obnoxious stage - we feel angry and no longer want to be responsible for feelings of others.
emotional liberation - we respond to feelings of others out of compassion, never out of feat, guilt, or shame. We accept full responsibility for our own intentions and actions, but not for the feelings of others.

Requesting that which would enrich live

use positive language when making request

i.e. express what are you requesting instead of what you are not requesting.
make requests in clear, positive, concrete action language

vague language contributes to confusion, we might be requesting one thing, but the other person might understand it in different way and no one is to blame.

Make requests consciously

Simply expressing our feelings it might not be clear to the listener what we actually want.

accompany the requests with feelings and needs, otherwise they might sound like demands

Asking for reflection

Ask for reflection to make sure the message we send is the same as the message that was received.

ask the listener to reflect it back
show appreciation when the listener tries to meet your request for reflection
empathize with the listener if he doesn’t want to reflect back

Requesting honesty

After we express ourselves vulnerably we often want to know:

What the listener is feeling (“I would like to know what you feel about what I just said”)
What the listener is thinking (“I would like you to tell me whether you think that my proposal will go through”)
- note that we again want to use concrete language instead of asking vaguely (“What do you think about that?”)
Whether the listener would be willing to take particular action (“I would like to know whether you are willing to postpone the meeting”)

Making requests of a group

In groups time is waster when the speaker isn’t certain what response they want.

Requests vs. Demands

When other person hears demand from us they have two options: to submit or to rebel.

to tell if it’s demand or request observe what the speaker does if the request is not complied with
it’s demand if the speaker then criticizes or judges our decision
it’s demand if the speaker then lays a guilt trip
it’s request if the speaker then shows empathy toward the other person’s needs

Defining objective when making requests

Our objective is a relationship based on honesty and empathy. We shouldn’t want to change other people mind. Instead, our objective should be for others to change/respond but only if they decide to.

When making request, it is helpful to scan our minds for thoughts that automatically turn requests into demands:

He should be cleaning after himself
I deserve a raise
I have right to spend more time off

Receiving Empathically

Now let’s turn the things around and learn how to apply the same four-components to hearing what others are observing, feeling, needing, and requesting.

Don’t just do something, stand there

empathy requires us to focus full attention on the other person’s message
ask before offering advice or reassurance, e.g. don’t do following:
- advising (“I think you should …”)
- one-upping (“That’s nothing, wait till you hear what happened to me”)
- educating (“This could turn into a good thing”)
- consoling (“It wasn’t your fault, don’t worry”)
- sympathizing (“Oh, you poor thing…”)
- explaining (“I would have called, but …”)
- correcting (“That’s not what actually happened”)
- interrogating (“When did this started?”)
- shutting down (“Cheer up, there’s nothing to worry about”)
intellectual understanding blocks empathy, it doesn’t have to make sense, we just need to listen
no matter what others say, we only hear what they are
1. observing
2. feeling
3. needing
4. requesting
listen to what other people need rather than what they are thinking
sometimes we first need empathy before being able to give empathy

Paraphrasing

Reflect back to the other person by paraphrasing what you understand. The speaker will either confirm it or we gave him the opportunity to correct us. Another advantage of reflecting is that we offer the other party time to reflect on what they’ve just said.

paraphrase by question that reveals our understanding while bringing out anything that needs correction. Some examples:
- Are you reacting to how many days I was gone last week?
- Are you feeling hurt because you would like more appreciation of your efforts?
- Are you wanting me to tell you my reasons for saying what I just said?
important: always sense the speakers’ reality first (“Are you feeling hurt because …?” versus “How are you feeling?”)
in case we want to ask directly without sensing first, we should first express our feelings and needs (“I’m frustrated because I don’t understand what you need from me. Would you be willing to tell me what I’ve done that makes you see me this way?”)
reflect back messages that are emotionally charged
paraphrase only when it contributes to greater compassion (sometimes it isn’t necessary to paraphrase, only listen)
behind intimidating messages are merely people wanting us to meet their needs

Sustaining empathy

allow others to first fully express their feelings before turning our attention to solutions
staying with empathy allows the speaker to reach deeper levels of their feelings
speaker has received adequate empathy when:
1. we sense release of tension
2. the flow of words comes to a halt

The power of empathy

it’s hard to empathize with those that appear to posses more power, status, or resources
the more we empathize with one another the safer we feel

Using empathy to defuse danger

rather than put “but” into the face of angry person, empathize
listening for feelings and needs helps us see other people in better light

Empathy to revive a lifeless conversation

to bring conversation back to life: interrupt with empathy
what bores the listener bores the speaker too
it’s better to interrupt rather than pretend to listen

Empathy for silence

sometimes empathy lies in our ability to be present and nothing more is needed

Connecting compassionately with ourselves

use NVC to evaluate yourself in ways that engender growth rather than self-hatred
avoid the should as in “I should have known better” or “I shouldn’t have don that”.
connect with feelings and needs stimulated by past actions that we regret
self-forgiveness: connecting with the need that we tried to meet when we took the action that we now regret
be ever of the needs behind our actions

Expressing anger fully

we are always angry because of ourselves, not because of what other people do or say, it’s a choice
steps to expressing anger:
1. calm down
2. identify our judgmental thoughts
3. connect with our needs
4. express our feelings and unmet needs

Conflict resolution and mediation

learn to hear needs instead of how people express them
avoid criticism and diagnoses
people often need empathy before they hear what’s being said
maintaining respect is key to successful conflict resolution
use role-play to speed up the process

Protective use of force

two questions that reveal the limitation of punishment:
1. What do I want this person to do?
2. What do I want this person’s reasons to be for doing it?

Expressing appreciation

“thank you” in NVC: “This is what you did, this is how I feel, this is the need of mine that was met.”

Thinking, Fast and Slow

matousdzivjak@gmail.com (Matouš Dzivjak) — Sun, 13 Sep 2020 00:00:00 +0000

Thinking, Fast and Slow is a book by Daniel Kahneman that explores the ways in which the human mind processes information and makes decisions. The book is divided into two parts, each focusing on one system of the human thinking.

“System 1” is fast, automatic, and effortless, and is responsible for intuitive and emotional responses. It is the part of the brain that we use when we quickly and automatically react to stimuli, such as when we reflexively jump out of the way of a speeding car. It’s also the part responsible for most of our cognitive biases.

“System 2”, on the other hand, is slow, deliberate, and effortful, and is responsible for logical and rational thinking. It is the part of the brain that we use when we consciously and deliberately think through a problem or decision.

Throughout the book, Kahneman uses a wide range of examples and experiments to illustrate the ways in which our two systems of thinking can influence our decision-making and behavior. He also discusses the various biases and heuristics that can affect our thinking, and provides practical advice on how to avoid common pitfalls and make better decisions.

Thinking, Fast and Slow is a fascinating and thought-provoking book that offers valuable insights into the human mind and how it processes information. For me it falls into the same (now pretty large) category of must-read books such as Factfulness, Enlightement Now, or Nonviolent Communication.

Notes

We operate on two systems
- System 1 automatic and quickly, little or no effort and no sense of voluntary control, runs automatically and can’t be stopped, error-prone
  - e.g. the fight or fleet response, orient to the source of sound, compare distance of objects, interpret facial experssions etc.
- System 2 effortful, allocates attention, hard to use for several activites at once, used when we need to compute or reason, slow but reliable
  - e.g. count occurances, focus on certain person in discussion, deliberately used to control System 1
Heuristics and System 1
- to quickly process stimuli System 1 relies on heuristics, often inaccurate
- heuristics:
  - associations and priming
    - associations - lime == green, doctor == clever, doesn’t have to be true
    - priming - common associations that move us in particular direction or action
    - e.g. if we are hungry we recognize the word soup easier, the effects are not large but can be used to affect people
  - cognitive ease
    - we are trying to get from system 2 (effortful) to system 1 (automatic)
    - e.g. you can make people believe falsehoods by frequent repetition, simple language, quotes, and memorable phrases
    - stocks with memorable/pronnounceable tickers do better over time
  - jumping to conclusions
    - WYSIATI = What You See Is All There Is - system 1 draws conclusions on readily available information
    - e.g. the confirmation bias = we are more open and looking for an evidence that confirms our believes
  - answeing the easier question
    - we simplify hard questions to easier once
    - e.g. “How happy you are with your life” to “What’s your current mood”
  - law of small numbers
    - small sample sizes - we make decisions on insufficient or unrepresentative data
  - anchors
    - priming the mind with an expectation
    - e.g. setting the intial bid in an offer very high primes the other party to bid higher
  - availability
    - we give more weight to recent events
    - good mood positively affect performance of system 1, on the other hand being tired makes it even worse
- biases and errors of sytem 1:
  - once wrong assumption is “accepted” it triggers associative mechanism, spreading relative ideas through our system
  - loss aversion - we prefer no changes even if they would benefit us in the long run

The Art of War

matousdzivjak@gmail.com (Matouš Dzivjak) — Sun, 26 Jul 2020 00:00:00 +0000

TODO

The Hard Thing about Hard Things

matousdzivjak@gmail.com (Matouš Dzivjak) — Fri, 19 Jun 2020 00:00:00 +0000

The Hard Thing about the Hard Things is book full of hard to swallow facts of running a successful business. Ben Horowitz with brutal honesty describes what all can go wrong, how to avoid it, and that eventually something always goes wrong. All of this with interesting and insightful stories from his time at Loudcloud.

The whole book is separated into discrete and short chapters on individual subjects of running a business. Be it chapter about hiring people for positions you know nothing about, telling your employees the bad news or even sacking your good friend. Ben always sums his knowledge into a few key takeaways that are easy to adopt and remember and even if you later want to learn more on some subject or just revisit a certain topic the book structure makes it easy to grab it and read a few pages on what you need.

The Hard Thing about the Hard Things contains plenty of examples and easy to grab concepts that can be adopted on many more places than just technological companies. The book covers a vast amount of topics so everyone will find a useful piece for himself. In the end you will know that there are no easy answers, but at least you can learn from mistakes of others.

This blog weights ~10kb

matousdzivjak@gmail.com (Matouš Dzivjak) — Sat, 06 Jun 2020 00:00:00 +0000

This website is tiny.

How it all started

Over last year I went over multiple iterations of this website and never really liked the result until now. I started with github pages, but these were restrictive and didn’t allow much customization and neat tricks. Second version was written in Next.js and I liked that quite more. I could easily do some cool stuff such as burger menu for mobile devices, animate my name in the title and more. Was it necessary? Nope. Was it cool? I will let you judge. But the page was quite heavy (400kb on first load) and I am the kind of person that likes things fast and optimized. I went down the rabbit hole of optimising the 💩 out of it. First, I removed every unnecessary dependency I could, bringing the size to ¾. Then I refactored the code to do as much as possible at the build time (such as loading info about my github projects). This reduced the size of the page to ½ of the original size. Better, still quite heavy though. As I was running out of ideas I also switched some libraries for others, I was using moment.js just to render how long ago was the blog post written, using timeago.js instead removed another 16kb from the first load.

This blog

Now? The landing page weights less than ~7kb (~3kb gziped). On the first load your browser will do exactly 2 requests, one for the page itself and second one for favicon (another ~1kb). Here are all the things I did to get this website to this state:

Got rid of javascript, now everything is static
Started using native fonts
Optimized css
Optimized the images
Removed all third parties
And finally, deleted everything unnecessary

Static website

I enjoy tinkering around with javascript, but the cost of doing so for such a simple site as this blog is too high. No one reads a blog because of the cool slideshows or nice animated menu. When the site was written in Next.js the client needed whole React juts so I could have my age displayed as constantly updating float number and load my projects from github dynamically. Next.js was overkill and didn’t allow me to optimize to the extend I wanted to.

Now this website is build using hugo. I can write the posts in markdown the same way I did before. I can use custom templates, styles, URLs, etc. the same way I did before but in the end everything gets compiled into tiny teeny static html files.

Native fonts

Using native fonts has two huge benefits over custom fonts included either in the css or loaded from for example Google fonts. First, the browser doesn’t have to download any font files before displaying the page. This reduces the amount of data transferred when someone visits your website and allows the browser to render the page as soon as it has the content instead for waiting for the fonts to load. The second benefit is that your website will look familiar to the user because they are used to seeing the font all the time at their device, be it iPhone or Windows PC.

Using native system font stack is super easy:

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif,
    "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol";
}

css-tricks: System Font Stack

Optimized CSS

I wanted my page to be nice and minimalistic, not much css was needed. First, I really like big bold headings, so I made all the heading a little bit more fat and reduced the spacing by a notch.

h1, h2, h3, h4, h5 {
  font-weight: 800;
  letter-spacing: -0.03rem;
}

Another little touch was changing the color of highlighted text:

::selection {
	background: #79ffe1;
	color: black;
}

Since I want the content to be readable even on large screens I put all the content into wrapper with maximum width and a little padding to keep some space around on smaller devices:

.wrapper️ {
	max-width: 720px;
	padding: 0 20px;
	margin: 0 auto;
}

One thing that I have seen on some other pages and blogs and that I am especially fond off is making the images and pictures full width while keeping the content padded. This can be achieved simply using following style with the previous definition for .wrapper.

img {
  width: 100vw;
  max-width: 720px;
  margin: 0 -20px;
}

Web Typography

Support for dark mode

Nowadays adding support for a dark mode is easy peazy. First, you define the colors as global css variables.

:root {
  --foreground: #111;
  --background: #fff;
  --light: #666;
}

Since this blog is really plain 3 variables were all that was needed. Then you add media query for dark mode and change the variables accordingly. In my case:

@media (prefers-color-scheme: dark) {
  :root {
    --foreground: #fff;
    --background: #111;
    --light: #aaa;
  }
}

Of course this won’t work if you don’t use the variables anywhere, so the next step was adding a few lines here and there:

body {
  color: var(--foreground);
  background-color: var(--background);
}

a {
	color: var(--foreground);
}

Just like that in a few lines of css your website spares the readers eyes in the evening and respects users preferred color scheme.

Optimize images

Optimized images are probably the biggest bandwidth saver. For this blog I have 5 sources for each image. I always keep the original plus generate .webp and .jpg images with width 760px and 1520px width. The smaller size should be enough for most devices because the content has max width of 720px (I left a slight buffer in case I would like to change that). The bigger images serves devices with higher pixel density. I then use following Hugo shortcode to place the images into the page:

{{ $id := (.Page.Resources.GetMatch (.Get "src")).Name }}
{{ $id = strings.TrimRight (path.Ext $id) $id }}
<figure>
  <a href="{{(.Page.Resources.GetMatch (.Get "src")).RelPermalink}}">
    <picture>
      <source srcset="{{ (.Page.Resources.GetMatch (print $id "_760.webp")).RelPermalink }}, {{ (.Page.Resources.GetMatch (print $id "_1520.webp")).RelPermalink }} 2x" type="image/webp">
      <source srcset="{{ (.Page.Resources.GetMatch (print $id "_760.jpg")).RelPermalink }}, {{ (.Page.Resources.GetMatch (print $id "_1520.jpg")).RelPermalink }} 2x" type="image/webp">
      <img alt="{{ .Get "alt"}}" loading="lazy" src="{{ (.Page.Resources.GetMatch (print $id "_760.jpg")).RelPermalink }}">
    </picture>
  </a>
</figure>

Let’s break it down:

{{ $id := (.Page.Resources.GetMatch (.Get "src")).Name }}
{{ $id = strings.TrimRight (path.Ext $id) $id }}

First line gets the resource (the image in this case) and assigns its name to variable $id. This serves the purpose of returning an error if the resource wasn’t available, the name was misspelled or the image wasn’t available in any other way. The second line extracts the file path without the extension, this is then used to obtain links to various versions of the image:

    <picture>
      <source srcset="{{ (.Page.Resources.GetMatch (print $id "_760.webp")).RelPermalink }}, {{ (.Page.Resources.GetMatch (print $id "_1520.webp")).RelPermalink }} 2x" type="image/webp">
      <source srcset="{{ (.Page.Resources.GetMatch (print $id "_760.jpg")).RelPermalink }}, {{ (.Page.Resources.GetMatch (print $id "_1520.jpg")).RelPermalink }} 2x" type="image/webp">
      <img alt="{{ .Get "alt"}}" loading="lazy" src="{{ (.Page.Resources.GetMatch (pringt $id "_760.jpg")).RelPermalink }}">
    </picture>

Link wraps the whole picture and points to the original full-sized image. This way readers can click and view the raw image in its whole glory.

I use imagemagick to generate different sizes and versions. First I did it manually like so:

convert -resize 760 img.jpg img_760.webp && convert -resize 760 img.jpg img_760.jpg

But it got quite boring over time so now there’s a script in place that does that for me.

How to setup you terminal on MacOS for powerusers

matousdzivjak@gmail.com (Matouš Dzivjak) — Sun, 17 May 2020 00:00:00 +0000

If you spend a lot of time in terminal and want to get the most out of it, this is the guide for you. I will go through MacOS terminal setup from zero to “GUI? Why would use that?”. Before you get started, I must warn you, this is an opinionated guide and I will mostly recommend what I personally like and use. Have that in mind and don’t forget to try multiple things, to see what fits you best. Also, this guide is mostly to show all the fun stuff you can do from terminal. If you want to learn useful things with basic terminal setup try The Art of Command Line.

If you don’t have any experience with terminal but would like to learn more, try starting with this introduction Discovering the terminal. When you get more confident with terminal feel free to return here and learn more!

Install Homebrew

Homebrew is a free, open-source software package manager for MacOS (and Linux too) that simplifies installation of applications and packages on your system. Simplifies might be an understatement here because with it doesn’t get much easier than writing brew cask install microsoft-word.

To install Homebrew run:

/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install.sh)"

This will take you through the installation process. Before any changes the script will inform you what it will do and will wait for your confirmation. When the script completes you are all set and done. From now on, you can install and update almost anything using Homebrew. Your daily usage of homebrew will consist of brew install [aplication] and brew cask install [aplication]. In general, brew install is for CLI tools and applications, and brew cask install is for full-featured GUI applications that you would otherwise install by downloading their binary from the website or app store. And once in a while, if you remember, update all your tools to their latest version using brew upgrade.

Brew has of course many more features but for the purpose of this article we won’t need much more. If you still want to learn more, visit the official documentation.

Install iTerm 2

iTerm 2 is terminal emulator for MacOS that has plenty of cool features and settings. You don’t need it and can use the default Terminal.app that comes shipped with all MacOS distributions but you would deprive yourself of many cool features.

brew cask install iterm2

Among the many cool features of iTerm 2 you will find things such as split pane, paste history, profiles, trigger, and much more. You can read about the various feature here.

Now, you might not like the default colors of iTerm 2. Before changing the theme though, I recommend you finish the ZSH installation so your terminal actually uses some colors, because by default, it doesn’t. To try out multiple color themes first download the color themes zip file from iterm2colorschemes.com/. Unpack it and then go to your iTerm to iTerm 2 > Preferences... > Profiles > Colors. In the bottom right corner click Color Presets... > Import... and select all the themes in schemes folder in the extracted directory. This will import all the themes into iTerm and you will be able to easily change them by selecting them from the Color Presets. Eventually you will find out which one you like, or you will get stuck changing them forever, who knows…

The theme is really a matter of personal preference. I was looking for a dark theme with high contrast colors and found out, that the Symphonic theme suits me the best. You go ahead, I try out what is best for you.

Install ZSH

ZSH or Z Shell is shell designed for interactive use. ZSH incorporates many features from other shells such as bash, ksh, or tcsh. This includes but is not limited to: file globbing, shell functions, aliasing, parameters substitution and more. To install ZSH run:

brew install zsh

Install Oh My Zsh

“Oh My ZSH!” is a open source, community-driven framework for Zsh configuration management. It comes bundled with functions, helpers, plugins, themes, and more… Install Oh My ZSH by running:

sh -c "$(curl -fsSL https://raw.githubusercontent.com/robbyrussell/oh-my-zsh/master/tools/install.sh)"

Best thing about Oh My Zsh is the plugins, you can find most of them in the exhausting Plugins Overview and there’s even more exhausting list without descriptions on the Plugins wiki page. Plugins are enabled by listing them in plugins variable in your ~/.zshrc and Oh My ZSH will take care of the rest (installation, updates, etc.).

# ZSH plugins
plugins=(
  git
  docker
  copyfile # copy the content of a file
  encode64 # encode to base64
  extract # extract any type of archvie
  web-search # search for something on internet: ddg cat, google dog
  git-extras # super cool autocompletion for git command
  httpie # completion for httpie
  catimg # cat but for images
  ...
)

Oh My ZSH provides also tones of themes to select from, all listed ZSH Github Wiki - Themes Page but in this tutorial, we will install Powerlevel10k, the one that I like the most (and trusty me, I have tried quite a few).

Install Powerlevel10k

Powerlevel10k is a theme for Zsh. It emphasizes speed, flexibility and out-of-the-box experience.

Indeed, Powerlevel10k is super fast, flexible and can be configured to your liking. If you want to experience the speed yourself, I recommend installing Powerlevel9k first and sticking with it for a few days, then installing Powerlevel10k, you won’t believe your eyes. Install Powerlevel10k using:

git clone --depth=1 https://github.com/romkatv/powerlevel10k $ZSH_CUSTOM/themes/powerlevel10k

And set ZSH_THEME="powerlevel10k/powerlevel10k" in ~/.zshrc. To configure the theme and set style and options that you prefer run:

p10k configure

This will take you through the setup process where you will step by step select what you prefer and like. If you are unhappy with the result it’s ok to run the p10k configure again.

I use the Pure setup because I used Pure before, liked the lean and clear style, but missed the speed of powerlevel.

Shell productivity

Above programs and tools provide many features that can speed things up but first one needs to learn them. Since writing about shell shortcuts, navigation, expansions, etc. would be for one article itself I will just point you to this awesome Shell productivity tips and tricks guide by Balthazar Rouberol.

The Fun

We installed Homebrew, iTerm 2, ZSH, Oh My ZSH and Powelevel10k; if you still bare with me - now the fun begins, I promise. We have nice, lean and fast terminal but what kind of amateurs would we be if we didn’t do absolutely everything we can from the comfort of commandline. For example, what if you want to check what’s the weather like? Pretty simple right? We can google it. But that would be lame and simple, instead, lets add the following function to our ~/.zshrc:

weather(){
  if [ $# -eq 0 ]; then curl wttr.in; else http "wttr.in/$1"; fi
}

then source the ~/.zshrc file: source ~/.zshrc and try it out:

$ weather berlin
Weather report: berlin

    \  /       Partly cloudy
  _ /"".-.     -1..+1 °C
    \_(   ).   → 6 km/h
    /(___(__)  10 km
               3.0 mm
                                                       ┌─────────────┐
┌──────────────────────────────┬───────────────────────┤  Mon 30 Mar ├───────────────────────┬──────────────────────────────┐
│            Morning           │             Noon      └──────┬──────┘     Evening           │             Night            │
├──────────────────────────────┼──────────────────────────────┼──────────────────────────────┼──────────────────────────────┤
│    \  /       Partly cloudy  │               Overcast       │      .-.      Heavy snow     │  _`/"".-.     Patchy heavy s…│
│  _ /"".-.     -1..+2 °C      │      .--.     1..4 °C        │     (   ).    0..3 °C        │   ,\_(   ).   -2..+2 °C      │
│    \_(   ).   → 13-15 km/h   │   .-(    ).   → 17-19 km/h   │    (___(__)   ↘ 11-14 km/h   │    /(___(__)  ↖ 14-20 km/h   │
│    /(___(__)  10 km          │  (___.__)__)  10 km          │    * * * *    4 km           │     * * * *   8 km           │
│               0.0 mm | 0%    │               0.0 mm | 0%    │   * * * *     2.7 mm | 66%   │    * * * *    1.0 mm | 21%   │
└──────────────────────────────┴──────────────────────────────┴──────────────────────────────┴──────────────────────────────┘
                                                       ┌─────────────┐
┌──────────────────────────────┬───────────────────────┤  Tue 31 Mar ├───────────────────────┬──────────────────────────────┐
│            Morning           │             Noon      └──────┬──────┘     Evening           │             Night            │
├──────────────────────────────┼──────────────────────────────┼──────────────────────────────┼──────────────────────────────┤
│    \  /       Partly cloudy  │               Overcast       │               Overcast       │  _`/"".-.     Patchy snow po…│
│  _ /"".-.     -1..+2 °C      │      .--.     2..4 °C        │      .--.     2..3 °C        │   ,\_(   ).   0 °C           │
│    \_(   ).   ↓ 10-11 km/h   │   .-(    ).   ↗ 11-12 km/h   │   .-(    ).   → 9-10 km/h    │    /(___(__)  ↗ 9-12 km/h    │
│    /(___(__)  10 km          │  (___.__)__)  10 km          │  (___.__)__)  9 km           │      ‘ * ‘ *  10 km          │
│               0.0 mm | 0%    │               0.0 mm | 0%    │               0.0 mm | 0%    │     * ‘ * ‘   0.0 mm | 0%    │
└──────────────────────────────┴──────────────────────────────┴──────────────────────────────┴──────────────────────────────┘
                                                       ┌─────────────┐
┌──────────────────────────────┬───────────────────────┤  Wed 01 Apr ├───────────────────────┬──────────────────────────────┐
│            Morning           │             Noon      └──────┬──────┘     Evening           │             Night            │
├──────────────────────────────┼──────────────────────────────┼──────────────────────────────┼──────────────────────────────┤
│    \  /       Partly cloudy  │               Cloudy         │  _`/"".-.     Patchy rain po…│               Overcast       │
│  _ /"".-.     0..4 °C        │      .--.     4..7 °C        │   ,\_(   ).   3..6 °C        │      .--.     2..5 °C        │
│    \_(   ).   ↗ 17-21 km/h   │   .-(    ).   → 18-21 km/h   │    /(___(__)  → 16-24 km/h   │   .-(    ).   → 15-24 km/h   │
│    /(___(__)  10 km          │  (___.__)__)  10 km          │      ‘ ‘ ‘ ‘  10 km          │  (___.__)__)  10 km          │
│               0.0 mm | 0%    │               0.0 mm | 0%    │     ‘ ‘ ‘ ‘   0.0 mm | 29%   │               0.1 mm | 52%   │
└──────────────────────────────┴──────────────────────────────┴──────────────────────────────┴──────────────────────────────┘
Location: Berlin [52.52045,13.40732]

Follow @igor_chubin for wttr.in updates

From now on, you don’t ever need to leave the command line if you need to know if it’s raining outside. And we are just getting started…

Essential CLI Tools

ag - The Silver Searcher - crazy fast code searching tool similar to ack.

Install with: brew install the_silver_searcher
jq - flexible and lightweight JSON processor that allows you to slice, transform, map and filter JSON data with eas.

Install with: brew install jq
HTTPie - curl/wget alternative with highlighting, JSON support, plugins and much more.

Install using: brew install httpie
fzf - command line fuzzy finder for anything. With fzf you can easily search for files, directories, commands from history and more using fuzzy matching.

Install using: brew install fzf
and to enable useful key bindings: $(brew --prefix)/opt/fzf/install

exa - modern alternative to ls. Exa ships with better defaults and colorful highlighting, it has also support for git, symlinks and file attributes and is written in rust, so it is super fast.

Install using: brew install exa

Example:

$ exa --group-directories-first -T go-nanoid
go-nanoid
├── examples
│  └── simple_example.go
├── go.mod
├── gonanoid.go
├── gonanoid_test.go
├── LICENSE
├── Makefile
└── README.md

noti - monitor for processes that triggers notification once the process completes. Nice thing for long builds, uploads or downloads, and other long running scripts.

Install using: brew install noti

Example: noti youtube-dl --extract-audio https://www.youtube.com/watch\?v\=iha_VCBfQMo

tldr - simplified man pages with examples, for whenever you forget the command usage and don’t want to read through thousands of lines of man page to find the flag you are looking for. (On the other hand, tldr is sometimes too brief).

Install using: brew install tldr

Example:

$ tldr cat

cat

Print and concatenate files.

- Print the contents of a file to the standard output:
   cat file

- Concatenate several files into the target file:
   cat file1 file2 > target_file

- Append several files into the target file:
   cat file1 file2 >> target_file

- Number all output lines:
   cat -n file

- Display non-printable and whitespace characters (with `M-` prefix if non-ASCII):
   cat -v -t -e file

Mackup - backup and keep your application settings in sync. Mackup supports multiple storages for backup - Dropbox, Google Drive, iCloud and more.

Install using: brew install mackup

Example: mackup backup
ffsend - easily and securely share files from the command line using Firefox Send. ffsend has also many useful features such as protecting the shared file with password or limiting the number of downloads.

Install using: brew install ffsend

Example: ffsend upload folder/ --archive --copy --no-interact --download-limit=1 (shares whole folder, zipped, limits the number of downloads to one and copies the URL of the file to your clipboard)
gist - upload content to gist.github.com. Gist makes it easy to share code snippets, simple markdown files and more, all from the command line.

Install using: brew install gist

Example: then gist -p -c README.md (creates private gist with README.md and copies the URL into your clipboard)
youtube-dl - download videos, audio or whole playlists from youtube.

Install using: brew install youtube-dl

Example: youtube-dl --extract-audio https://www.youtube.com/watch\?v\=iha_VCBfQMo
bat - cat alternative with colors and more.

Install using: brew install bat

Example: bat -A .gitconfig

Making it easier with aliases

I introduced you to tones of tools that you most probably already forgot before getting to this line. Also, if you are lazy like me, you don’t want to write the whole command every single time. Solution? Aliases. Lets type less and do more with following:

Navigation - here’s a few aliases that make the navigation easier

alias ..="cd .."
alias ...="cd ../.."
alias ....="cd ../../.."
alias .....="cd ../../../.."
alias ~="cd ~" # `cd` is probably faster to type though
alias -- -="cd -" # switch between old and present working directory

Alternatives - I use a lot of alternatives to common tools so I override them using aliases

alias cat="bat"
alias download="http --follow --download"
alias diff="colordiff"
alias diff="colordiff"
alias rm="trash" # this is a live saver
alias ls="exa --group-directories-first"

Shortcuts - lets create shorter names for commands that are used often

alias g="git"
alias reload!='. ~/.zshrc'
alias x="exit"
alias sz="source ~/.zshrc"
alias ls="exa --group-directories-first"
alias lst="exa --group-directories-first -T"
alias ll="exa --group-directories-first -l"
alias la="exa --group-directories-first -a"
alias lat="exa --group-directories-first -a -T"
alias path='echo -e ${PATH//:/\\n}'

Fun - some other fun shorthands that are pretty much useless but nice to have.

# Stuff I never really use but cannot delete either because of https://xkcd.com/530/
# original aliases used 'muted true' instead of 'volume 0', I find this better
alias stfu="osascript -e 'set volume output volume 0'"
alias pumpit="osascript -e 'set volume output volume 100'"

alias afk="/System/Library/CoreServices/ScreenSaverEngine.app/Contents/MacOS/ScreenSaverEngine"
alias sleep="pmset sleepnow"

Functions

Last but not least, there are things for which aliases are short or you need additional logic. That’s where function come in handy, again, here’s a list of the ones I use in no particular order. (Except the first one, that’s my love).

Share anything from command line - I already talked about the ffsend command for sharing but this functions takes it step further:
```
# share file for one download only, uses https://github.com/timvisee/ffsend
share(){
  ffsend upload $1 --archive --copy --no-interact --download-limit=1
}
```
This function will: archive the file (or files, or directory), upload it, set the download limit to 1 download and copy the link to the sharable URL to your clipboard. Pretty neat right! I use this anytime I get a request to share some photos (in reasonable size) or documents.

Git Aliases

To speed up the development I also use bunch of git aliases so I can type less and do more. These are mostly individual and depend on personal preferences but one that I found especially useful in my day to day use is cane = commit --amend --no-edit. In our team at Kiwi.com we always do 1 commit per MR, this means that I often add changes to already pushed commits and this alias makes it super easy and fast.

[alias]
  w = switch
  hist = log --pretty=format:'%h %ad | %s%d [%an]' --graph --date=short
  type = cat-file -t
  dump = cat-file -p
  c = commit
  b = branch
  s = status
  p = pull
  d = diff
  lo = log --oneline -n 10
  unstage = reset HEAD
  pushf = push --force-with-lease
  cane = commit --amend --no-edit
[apply]
  whitespace = fix
[credential]
  helper = osxkeychain
[push]
  default = current
[rerere]
  enabled = true

Other sources

Backpacking Georgia in 14 days

matousdzivjak@gmail.com (Matouš Dzivjak) — Tue, 05 May 2020 00:00:00 +0000

🚧 Work in progress 🚧

In 2017 a friend of ours got an opportunity to work at the Czech Embassy in Tbilisi (Georgia) which she gladly took. Terka, a sister of my very good friend Dominik, went with her to take care of her children. Soon after we were offered accommodation in case we decide to visit them which put all things into motion. Not even a week after we had our plane tickets bought and already were planning the itinerary, so that we could squeeze the most out of our 2 weeks in Georgia.

Planning our Georgia trip proved to be harder than we though as the tourism there is in its infancy. We also wanted to spend most of our time trekking in mountains which we found even less information about. In the end we had a list of a few places and things we would like to see but no concrete plan what so ever. Our initial plan consisted of: 1 or 2 days in Tbilisi to explore the capital. 2 to 3 days to visit and trek around Lagodekhi, easternmost town located at the foot of the Greater Caucasus mountains in the historical region of Kakheti. 2 to 3 days for the Tusheti national park in the north-eastern part of the country. We also wanted to visit the townlet of Stepantsminda from where the third highest mountain of Georgia - Mount Kazbek (5033m) can be seen. We then planned to move to the west of the country and walk the hanging bridges over Okatse Canyon located close to the town of Martvili. Around Martvili there are two more points of interest - Martvili Canyon that is usually explored on boats and Martvili Monastery. Not so far, near the town of Kutaisi, lays Sataplia Strict Nature Reserve and famous Prometheus Cave which is over 11 km long (1060m are open to visitors). From Kutaisi, we planned to return to Tibilisi and catch our flight home; back to Prague.

Spoilers alert, our plans changed quite a bit, and we didn’t visit even half of the places mentioned before. Nevertheless, we have seen and experienced a lot and remember Georgia as one of the best trips up to this date.

Tbilisi

Tbilisi is the capital and the largest city of Georgia. It has population of approximately 1.5 million people and lies on the banks of the Kura River. Throughout history Tbilisi was a point of contention among various global powers, mainly because of its location on the crossroads between Europe and Asia. Tbilisi is important transit route to this day.

More buildings were being build than standing. Tbilisi is currently growing at enormous speed and often modern buildings stand next to falling apart remains of old houses.

Tusheti National park

We hitched a hike that saved us one day of walking and enjoyed beautiful views from the back of the car.

Stray dog trekked with us for 2 days, it seemed as if he enjoyed it more than us.

Nothing but plains and Atsuna pass in the far.

With Atsuna pass behind us we raised our tempo and with the vision of civilisation in front of us covered over 35km in one day.

Good and warm food, beer, and chacha with Coca Cola (offered by Polish guys sitting by the next table) was all that we needed after 5 days in mountains.

Batumi

Mtskheta

Davit Gereji Monastery

Food

This huge Shavarma got obliterated in under 5 minutes.

Dominik and Terka enjoying ice cream on our last day in Gerogia.

Cryptographic Hash Functions explained

matousdzivjak@gmail.com (Matouš Dzivjak) — Wed, 08 Apr 2020 00:00:00 +0000

Hash function is a mathematical function that takes arbitrary input and maps to fixed-size value. Here’s a little example of a hash function that maps input to 4 digits number.

h("dog") = 1571
h("Hey, that's a beautiful cat you've got over there!") = 9801
h("c") = 0130

Cryptographic hash function is a hash function with more restrictive properties that has many applications in cryptography, encryption and security in general. Here’s an example of modern hash function that is used in some way to secure almost all the internet traffic.

sha-3("turtle") = 38b33b6f08b5cd5428ddc7aa698d7e8a0a2f15830ef17b9dbb518699f850a141

Before we get into hash function characteristics, lets try to design a hash function ourselves. We will start with something simple, for example a function that takes a number and returns its reminder after dividing it by 10 (this operation is also called modulo).

h(x) = x mod 10

A few example:

h(33) = 3
h(182) = 2
h(10) = 0
...

Does this function take an arbitrary input and returns fixed-size output? Yes, it does. Is it a good cryptographic hash function? Well, no it isn’t. To make a hash functions useful in cryptography we introduce further restrictions.

Properties

First one is Pre-Image Resistance. What this property means is, that it should be hard to reverse the hash function. In other words, knowing the value that came out of the hash function should provide zero to none information about what came in. Here our previously defined function fails. Knowing the value that came out means knowing the last digit of the number that came in.

Let’s try to fix that and change our hash function. Now we will add random number to the input before doing what we did before, taking the reminder of division by 10. This function still returns fixed-size value, furthermore, it is no longer possible to tell anything about the input. Do we have a good hash function? Not yet.

Another property that good hash functions should have is being Deterministic. Deterministic function always maps the same input to the same output. Our function doesn’t do that. Number 100 can be mapped to 1, 4, or any other number depending on the random value we add.

There are two more properties that we need that are hard to show on easy functions. First one being Efficiency. Hash functions must be fast to compute to be usable. It should be easy to compute the output for any value but really hard to find input for given output. This is partially overlapping with Pre-Image Resistance, and we call such function a One-way Function.

The last property of hash functions is Collision Resistant. That means that it must be extremely unlikely (read “virtually impossible”) for two inputs to produce the same output. That’s hard to imagine on the example that we set with a function that has 10 possible outputs but take for example SHA-3, modern secure hash function that is the current standard. This function has

2^256 = 115792089237316195423570985008687907853269984665640564039457584007913129639936

possible output values. Such a huge output space makes it practically impossible to find two inputs that map to the same output.

We have covered the 4 base properties of good and secure hash function. Pre-Image Resistance, being Deterministic, Efficiency and Collision Resistance. Now lets show why these properties are important on some real life examples.

Applications

Cryptographic hash functions are a basic tool of modern cryptography and have many applications in fields such as digital signatures, fingerprinting, message authentication and other forms of authentication, and more.

Data integrity

First application that we will look into is data integrity verification. How that works is that we take a message, file, or any other digital medium, we create message digest (compute the hash function value for given message or file) and any time we need to verify the integrity we compute the message digest again and compare it with the original. This way we can determine whether any changes of modifications have been made to the original message or file during transmission.

Message digests are for example published by many websites to allow verification of integrity of downloaded files. The whole process looks like this: an author creates application or file that he wants to publish securely for public. He creates message digest for given file and publishes it alongside the file on his website. User downloads the file, computes message digest using the same cryptographic hash function as the author did and compares the digest with the one published by the author. This way he can verify that the files hasn’t been tempered with during the download. This method isn’t bulletproof because the hash on the website could be tempered but as long as we trust the website we can trust the downloaded file as well.

Digital Signatures

Other application of cryptographic hash functions are Digital signatures. Digital signatures are closely related to Data integrity, they again allow you to verify data integrity. Furthermore, digital signatures tie the signer to the document making it hard for the signer to deny signing the document. This property is called non-repudiation and refers to a situation where author cannot dispute validity or authorship of associated document.

To create a Digital signature the author creates message digest and signs it using his private key. Digital signature is then distributed alongside the document or file. If anyone wants to verify the signature he needs to compute the message digest on his side, decrypt the signature using authors public key, and compare the two message digests. This way he can verify not only the integrity of the data but also the authorship. Private key in this case works sort of like a credit card pin, it is something that only the owner knows so signing the message with his private key ties him indisputably to the signed document.

Digital signatures are used for example by The United States Government Printing Office (GPO) to sign electronic versions of the budget, public and private laws, and congressional bills.

Passwords

Cryptographic hash functions are also the safest way of storing passwords. All major websites and applications (facebook, google, etc.) use hashing for password storage and user authentication, and if they don’t, they should.

To show how that works lets start with a bad example of how passwords shouldn’t be handled. A bad but straightforward approach to password authentication is prompting the user for a password and then storing the password as the user entered it alongside his username or email on the server. To authenticate the user all that is need is to compare the entered password with the stored one, if they match, the user successfully authenticates. Where this approach lacks though is when things go south and malicious party steals the credentials from the server - suddenly they have information about all users tied with their passwords.

Good approach is hashing the password before storing it on the server. This way at any point in time the only person that knows the password is you. To authenticate you the server computes the hash again and compares it with the stored one. Now even if someone steals the credentials he has no way of retrieving your password from the hash (thanks to the Pre-Image Resistance property).

Why We Sleep

matousdzivjak@gmail.com (Matouš Dzivjak) — Thu, 19 Mar 2020 00:00:00 +0000

In my first years of university, I often found myself doing homework up to the early morning hours and then sleeping a few hours and starting the new day as if nothing happened. I knew that it wasn’t good, but only now I know how bad it was. Bad sleeping habits make you fatter, sicker, unhappier, more forgetful and prone to diseases shrinking your life expectancy with every night that you don’t rest well.

Why We Sleep by Matthew Walker, the director of UC Berkeley’s Center for Human Sleep Science, is filled with striking information about the effects of lousy sleeping habits. Walker explains how neglecting a good night rest affects our problem-solving abilities, memory, creativity, mental and physical health, as well as social feeling and empathy.

Even though Walker sometimes jumps very far from the correlation to causation in things such as the relation between sleep length and happiness, the book is still essential and alarming in many ways. Here are some facts that stuck with me and that you might be asking yourself even before reading the book.

How long do we have to sleep

You might think that you are a short sleeper, and 6 hours per night are enough for you, most likely, that’s not the case. Only less than 1 percent of people can sleep 6 hours and get the amount of sleep that their body needs; the rest is sleep-deprived and got used to it. The optimal amount of sleep is 7,5 - 8 hours every night. If that’s not possible for you, try to take a quick nap after the lunch, even though it can’t substitute the night sleep it’s still better than letting your tired body flow through the day without a rest.

Sleeping habits also change with age. The thing that I could closely relate to is that in the puberty, our sleeping cycle moves forward, making us want to stay up longer and sleep until later hours. The body often overshoots this shift, which might last up until adulthood. Thus it is very important to let your adolescent kids sleep long enough, which is often impossible with early school schedules.

What if we sleep less

Why We Sleep lays out so many negative effects of sleep deprivation that it would take more than ten articles to list them all. Things that take the highest toll are memory, concentration, creativity, and the overall state of health of your body. Walkers also links sleep deprivation to many diseases, why the linkage might not be as strong as he claims, what has been proven to be true over and over again is that being drowsy behind the wheel is as bad as being drunk.

\[1\]

Fatigue-related accidents are estimated to account for 20% of fatal car crashes. Driving after 24 hours without sleep is considered to be equal to driving with 0.1% alcohol in blood, the amount considered illegal in almost all countries.

How to improve your sleep

There are a few things you might consider doing to improve your sleep. First is avoiding blue light before going to bed. Blue light boosts your mood and energy, which is excellent throughout the day but is not desired in the evening when you want your body to relax and get ready for rest. Internally, your body thinks that the blue light is the natural light and it suppresses production of melatonin, a hormone that regulates our sleep-wake cycle by making us feel tired.

Secondly, you can create a better environment for the shut-eye phase of the night, make sure your room is dark, silent and cold, your body drops the temperature in the night and you will rest better if your body doesn’t have to work hard to do that. Optimal room temperature for sleeping is around 19 °C (65-66 °F).

\[2\]

If you like to take a hot bath before going to bed, however unpleasant, consider taking a cold shower at the end.

Last but not least, try to avoid alcohol before bedtime; contrary to the popular believe alcohol doesn’t improve your sleep, rather it induces the sleep but lowers the overall quality (mostly of the REM - rapid-eye-movement phase) to very low level. That’s also the reason why even after sleeping to the lunch hours after a party, you still feel tired, and your body asks for more sleep.

Why we sleep at all

After all, sleeping makes you - and all animals alike - vulnerable and unable to hunt, gather, reproduce, or eat. Why do we sleep then, and why hasn’t the evolution got rid of the sleep already? Because the upsides of sleep overweight the downsides severally. Sleep helps us regenerate and boosts our immune system, while we sleep the body gets rid of many toxic substances and enhances our abilities using the experiences obtained throughout the day. Overall, sleep makes us evolutionary more fit, just in ways that are not that easy to see.

Summary

Why We Sleep is both eyes-opening and eyes-closing book. Never have I been proven to be wrong in so many things by a book. Walker also encourages you to put the book often away and take a nap or go to sleep already, knowing how important sleep really is. I think we all should learn more about sleep - an activity we spend almost one-third of our lives at and yet know so little about. That being said, the books has its flaws and factual errors, you can read more about these for example in this article: Matthew Walker’s “Why We Sleep” Is Riddled with Scientific and Factual Errors.

Critics

Alexey Guzey wrote lengthy article titled Matthew Walker’s “Why We Sleep” Is Riddled with Scientific and Factual Errors that debunks and disputes many claims in the book, to name a few:

No, shorter sleep does not imply shorter life span
No, a good night’s sleep is not always beneficial
No, lack of sleep will not outright kill you
No, two-thirds of adults in developed nations do not fail to obtain the recommended amount of sleep
and many more…

I definitely recommend reading the blog post as well as the discussions linked in the first paragraph.

Learn more about sleep

\[1\] - Drowsy Driving
\[2\] - This Is the Best Temperature for Sleeping, According to Experts

Never Split the Difference

matousdzivjak@gmail.com (Matouš Dzivjak) — Mon, 02 Mar 2020 00:00:00 +0000

In Never Split the Difference Chris Voss, the author, explains why most of what we have been thought about negotiation is wrong and that concepts such as fairness and rational decisions do not exist. The real negotiation doesn’t start or end with Yes but rather with No. This book will make you appreciate hearing No more often, and you will learn that No often gets you further then Yes.

Chriss Voss is a battle-tested FBI negotiator with years of experience with life-or-death situations. In Never Split the Difference, he not only shows what works but also why. His teaching is based on real-life, experience not only with hostage situations but also with teaching and guiding people in business to close the best deals possible.

We spend a lot of our lives unknowingly negotiating, so we might as well get better at it. Never Split the Difference provides a strong foundation for negotiation with many easy and useful takeaways. What sets this book and techniques in it apart from others is the focus on empathy and emotional intelligence. These leanings were game-changers for FBI, and Voss brings them into real-life situations with lively examples and stories from his clients.

Be a Mirror

Concept of Being a Mirror stuck with me the most and has already helped me tremendously in my everyday life. Mirroring works by repeating words of what someone has just said back to them. Mirroring makes your counterpart elaborate, often yielding more vital information for you. People fear difference and are drawn to similarities. Mirroring evokes the feeling of bonding which encourages the other side to keep talking and often reveal more then they wanted to. This skill is also very convenient for keeping conversation up and running with whoever you might want to, if it’s your boss, new teammate, or potential significant other.

Listening and labeling

Voss stresses it multiple times through the book - listing is the key. People want to be heard and understood. Listening is a cheap and easy way to demonstrate empathy and show a desire to hear more. Another essential skill to learn is labeling. Labeling means naming someone’s emotions, acknowledging them, and letting them now that you identify and understand their feeling. To label an emotion, you almost always begin with “It seems like…”, “It sounds like…”, or “It looks like…”. Once you throw the label into the open, it is good to stay quiet and listen. By naming (labeling) the emotions, we diffuse or defuse the bad ones and reinforce the good ones. Both these skills go hand in hand and will once again help you bond and build a more reliable connection with the counterpart.

Summary

Never Split the Difference might be your key to a better salary or happier relationship. This book has a ton to offer to absolutely anyone and does so in easy to understand manner. Voss’s writing is easy to follow, and all the concepts are clear, with plenty of examples and proofs.

If you want to learn more about the negotiation skills without reading the book, take a look at the following links:

Or print the Summary Cheat Sheet.

Economic Facts and Fallacies

matousdzivjak@gmail.com (Matouš Dzivjak) — Sat, 29 Feb 2020 00:00:00 +0000

Economic Facts and Fallacies is the second book by Thomas Sowell I have read, and I am again left in awe. The book repeats many themes already touched in Basic Economics but explains them more in-depth. Sowell does a beautiful job of providing many illustrative real-life examples to each topic covered that just bring the problematics so much closer to the reader. The examples make it easy to see the consequences of each and every economic decision examined in the book. Sowells writing is easy to consume and understand, but still caries value in every sentence.

Economic Facts and Fallacies covers a wide range of themes, these include many mistaken but widely disseminated beliefs, such as racial and male-female income differences, as well as economic fallacies about academia and Third World countries. Sowell focuses on the fallacies that are thought to be true not only by the public but also by many politics, economists, and media. Although the book takes a deep dive into individual chapters, it is easy to read and understand, requiring no prior knowledge of economics.

The most important takeaway for me was to learn about the Zero-Sum Fallacy, which is widely believed and propagated by media and politics alike. You might often hear that what is gained by someone must be lost by someone else. Nevertheless, such economic transactions wouldn’t voluntarily take place if they were not beneficial for both parties involved - whether employer and employee or two countries. An example might be developing countries that have kept out foreign investments and trade in fear of being “exploited.” However, eventually many once-poor places achieved prosperity by opening its markets to international trade and investments. This includes Hong Kong, South Korea, Singapore, and many others. Some are making their markets freer just now - China and India - with visibly good results, growing economics, and millions of people rising out of poverty.

Economics Facts and Fallacies is a very educational and easy to read book for anyone, even with the slightest knowledge of economics. After reading, you might change your view on many decisions made by governments, and will make you question a lot of claims made by politics and media.

Basic Economics

matousdzivjak@gmail.com (Matouš Dzivjak) — Sat, 22 Feb 2020 00:00:00 +0000

Basic Economics by Thomas Sowell, with its 650 pages, doesn’t exactly seem like basic even for someone with high quotient. But after all, I went through the book in less than 2 weeks and enjoyed every page.

Basic Economics was one of the most eye-opening books for me. It was the first book on economics that I have read and even though most of the terms and concepts were absolutely new for me I never had to re-read a page to grasp the meaning. Sowell does a great job of briefly introducing a topic and then slowly building on top of it with plenty of real-life examples and data supporting his claims and findings. Basic Economics for me wasn’t book only about economics but also about politics and the drivers and reasons behind what’s currently happening in the world. A lot of the knowledge from the book stayed with me until now, thanks to nice short summaries after every chapter and plenty of practical questions at the end of the book that you can try to answer with what you have learned.

Even with 650 pages and after many more economics books I have read in the last year I still consider Basic Economics to be the best one. There’s no book on economics I would currently recommend more. Whether you are interested in financial literacy or politics this book has a value for you, and you will most definitely find more interesting topics on your way through.

Keeping your finances at check with Ledger

matousdzivjak@gmail.com (Matouš Dzivjak) — Wed, 19 Feb 2020 00:00:00 +0000

For the last ~~three months~~ year, I have been keeping track of all my expenses and income using Ledger, and it slowly turned into a little obsession of mine. Here’s my take on what ledger is, how to keep one, and why you need one.

What is Ledger

Ledger is a double entry accounting system that is accessed from a command line and kept in simple text files. This is a lot of words for introduction, but all the terms will be explained in the following paragraphs. For now, all you need to know is that this is one of many ways of bookkeeping - recording of financial transactions. And that thanks to ledger, you will be able to know how much you are spending, on what, and where your money lies.

Double Entry accounting

In accounting, everything is based on accounts. An account is every type of expense, income, or a place that holds any monetary value. In double entry accounting each transaction is recorded as a flow between at least two accounts and it is required for the total amount removed from accounts to equal to the total amount added. This is a partial check that every transaction was correctly recorded, and no money was lost in the process. In practice, it means that adding 1000$ in one place (account) requires you to remove 1000$ from another place. The consequence of this is that the balance of all accounts is always zero.

For example, buying groceries for 42$ will be recorded as moving 42$ from Credit Card to Groceries account. In the same way, receiving 2000$ salary means a flow of 2000$ from account Salary to account Bank. While the names of the accounts are entirely up to you there are certain naming conventions. In general, you would have the following main accounts:

Expenses - where the money goes
Income - where the money comes from
Assets - where money sits
Liabilities - money you owe
Equity - the real value of your property

You can add further levels to the accounts as detailed as you need, for example, Expenses -> Fun -> Tickets -> Concerts.

Ledger

Ledger is a command line tool for double-entry accounting. It is an extremely versatile tool that takes some time to master but once learned it can be used seamlessly for both personal and professional accounting.

Documentation for ledger can be found at https://www.ledger-cli.org/ in pdf or html format. There’s also awesome Getting Started With Ledger tutorial by Rolf Schröder & Contributors where I took a lot of inspiration from, and that might help you get started. Finally, if you want just a brief introduction and want to learn the rest as you go, you can quickly scrim through Ledger CLI cheatsheet.

Working with Ledger

Working with Ledger consists of two distinct actions: updating the list of transactions in your journal file and using the ledger tool to view and interpret the recorded transactions. Ledger provides you with a set of tools to analyze and filter out the transactions recorded in your ledger files.

Following the groceries example from an introduction to the double entry accounting the transaction recorded in your journal file would look like this:

2020/04/14 Groceries
  Expenses:Groceries  $42
  Assets:Checking  $-42

Each transaction starts with a date and title of the transaction. The heading is followed by two or more lines of accounts involved in the transaction with the amount of money moved from or into the account. Lines with accounts (postings) start with whitespace, and the amount is separated by at least two whitespaces from the account. Two spaces are required because the account name itself can contain a space, for example, Expenses:Car Insurance or Expenses:Food and Drinks. The amount must sum up to zero (otherwise, it wouldn’t be a valid double entry accounting transaction). Ledger can calculate the appropriate amount for the last account for you so it would be valid and more comfortable to write:

2020/04/14 Groceries
  Expenses:Groceries  $42
  Assets:Checking

The journal file consists of transactions such as the previous one and some optional metadata. Following are some more illustrative examples to help get you started:

; Set up your initial state using opening balances
; This will be your first transaction
; (assuming you are not starting with zero money).
; '*' means that the transaction is cleared
; e.g., the money was moved from one account to the other.
2020/04/14 * Opening Balance
  Assets:Checking  $1490
  Assets:Savings  $3220
  Liabilities:Loan  $200
  Equity:Opening Balances

; Salary comes from your employer to your checking account.
2020/04/15 * Salary
  Assets:Checking  $1330
  Income:Salary

; Withdrawal means moving money from your checking account to cash.
2020/04/16 * ATM withdrawal
  Assets:Cash  $40
  Assets:Checking

; Payig for beer by cash.
2020/04/16 * The Pub
  Expenses:Fun:Beers  $12
  Assets:Cash

; Paying for your friend's beer because he doesn't have money.
2020/04/17 * The Pub
  Assets:Reimbursements  $8 ; Payee: Friends Name
  Assets:Cash

...

We will explain all the concepts more in-depth later on. Now let’s get started with ledger to make some sense of our transactions.

Installing Ledger

To get started with Ledger, first install it on your device. You can find everything on Ledgers download page.

MacOS

To install ledger or MacOS simply run

brew install ledger

Linux & BSD

Go to Ledger Cli Download Page and download the latest version of binary for your distribution.

Windows

It’s a little bit harder to get Ledger running on windows, but the simplest way to do so is to go to Ledger Binaries Download Page and download the binary for the Windows system.

Reports

Journal is an excellent way to keep track of transactions but doesn’t give as much information about our current financial situation and insight into our spending and income. This is where the Ledger tool comes in. Ledger tool provides you with a set of commands and tools to make sense of your journal. The most used commands for reporting are balance (bal) and register (reg).

Balance

The balance report creates total balance for all transactions. The most basic usage looks like this:

$ ledger -f ledger.txt bal[ance]

        $1720.00  Assets:Checking
       $-1200.00  Equity:OpeningBalances
         $220.00  Expenses
         $133.00    Food:Groceries
         $127.00    Unknown
       $-1000.00  Income:Salary
 ---------------
               0

Ledger, of course, allows you to do plenty of things with the balance. Including but not limited to:

# Restrict by date. Use -p or --period.
$ ledger -p "last 3 months" bal
$ ledger -p "this month" bal
$ ledger -p "2020" bal

# Balance by account name
$ ledger bal Expenses
$ ledger bal Assets and Liabilities

# Show subaccounts only until certain depth
$ ledger --depth 2 bal

Register

$ ledger -f ledger.txt reg[istry]

...
2020/04/15 Some Restaurant         Expenses:Food:Lunches             $7.00         $47.20
                                   Assets:Checking                  $-7.00         $40.20
2020/04/15 Some Coffee Shop        Expenses:Food:Coffee              $6.00         $46.90
                                   Assets:Checking                  $-6.00         $40.20
2020/04/15 Groceries Shop          Expenses:Food:Groceries          $10.00         $50.00
                                   Assets:Checking                 $-10.00         $40.20
2020/04/15 My Company              Assets:Checking               $1,500.00      $1,500.00
                                   Income:Salary:Company        $-1,500.00         $40.00
2020/04/15 Rent                    Expenses:Living:Rent            $200.00        $200.00
                                   Assets:Checking:Airbank        $-200.00         $40.20

Again, ledger allows you to do much more, often in the same way as with balance command:

# Restrict by period.
$ ledger -p "feb 2020" reg

# Group by week
$ ledger reg -W

# Show weekly expenses
$ ledger reg -W -n Expenses

# Show weekly expenses as total amount
$ ledger reg -W -n Expenses

There’s much more you can do. To see the full list of flags and commands, you can use, visit the official documentation.

Keeping a Journal

The essential part of Ledger and accounting, in general, is keeping a good journal. Ledger has been designed to make that as easy as possible with its simple format and by automatically determining us much information as possible. For example, if Ledger encounters posting with an unknown account, it will create it. Or if you use commodity, that the Ledger hasn’t seen before, it will create that commodity and automatically determine how to display it (placement of currency, display precision, thousands separator, etc.) based on how you used the commodity in the journal.

While the format as simple as possible, there are still two rules that need to be followed. First is that the start of the transaction is at the first line followed by accounts indented by at least one space. Secondly, there must be at least two spaces between the account and the amount. If you don’t follow these rules Ledger will report an error and exit.

Sometimes the flexibility isn’t desired and might lead to difficulties. In order to combat inconsistency, you can define accounts and payees beforehand and ledger will print error and exit if it encounters an unknown account or payee.

; Define your accounts
account Assets
account Assets:Cash
account Expenses
account Expenses:Utilities

Use --strict flag to enable the strict mode. Strict mode will print warnings but still calculate the results, if you want to force the consistency you can use --pedantic that will cause the Ledger to exit with error on undefined accounts and commodities.

$ ledger bal --strict
Warning: "journal.dat", line 6: Unknown account ’Asets:Checking’

If you already started a journal and would like to enable the strict mode, you can find out all the accounts that you use by running $ ledger accounts. To put them into your journal, you need to prepend them with account; this can be simplified by running $ ledger accounts | awk '{print "account " $0}'.

Advanced usage

You have seen some basic usage in previous sections, here are some more advanced concepts you will encounter with Ledger accounting.

Resetting a Balance

Sometimes your ledger account balance and real account balance values diverge. This might happen, for example, if you lose track of your cash spending. To bring the ledger back to order you can simply reset the balance to its current value using the = operator and Adjustents account.

2020/04/20 Adjusting Cash
   Assets:Checking  = $20
   Equity:Adjustments

Commodities

Ledger allows you to keep track of investments and multiple currencies. Investment is anything that is not in dollars (or whatever your default currency is). In the sense of Ledger, there’s no difference between stocks and currencies; both are handled the same way. It is only recommended to put currency symbols before the value and commodity symbols after it. To allow ledger to handle multiple commodities (we will use currencies and commodities interchangeably) it must know how to convert them. This is done by defining the commodity’s value in terms of another commodity. Most often, you would specify the purchase price of the commodity at the time of transaction.

2020/04/21 Stock purchase
  Assets:Broker  10 TSLA @ $420.00
  Assets:Broker

Now at the time of sale:

2020/04/22 Stock sale
  Assets:Broker                    -10 TSLA {$420.00} @ $500.00
  Income:Capital Gains             $-800.00
  Assets:Broker                   $5,000.00 ; you can ommit this value

The {$420.00} behind TSLA stock is a lot price. Lot price means that the price of the given commodity can differ for each lot. This allows you to track multiple investments in the same currency bought and different initial prices.

Sometimes the commodities are consumed and are not meant to be sold later. In that case, you want to fix the lot price, so it stays at the same as at the purchase time.

2020/04/23 Shell
  Expenses:Gasoline  40 L {=$1.5}
  Assets:Checking

On the background, this introduces a new commodity with fixed value L {=$1.5}.

Sometimes you also want to see the values in terms of a particular commodity. For example, you might have a lot of investments going on and would like to know your current total equity in terms of dollars. This can be done using the -X (--exchange) COMMODITY flag. The Ledger will convert all the commodity values based on the latest available price it can find.

Budgeting

Budgeting is another feature of Ledger. Budgeting allows you to control your income and expenses, by reporting on how far or close your actual financial activity matches your expectations.

To get started with budgeting, you define periodic transactions at the top of your ledger file. These transactions are almost identical to any other transactions you would record except that they start by tilde (~) and have period expression instead of the payee in the title.

~ Monthly
  Expenses:Rent  $500.00
  Expenses:Food  $450.00
  Expenses:Insurance  $150.00
  Expenses:Party  $50.00
  ; other expenses
  Expenses  $200.00
  Assets:Checking

~ Yearly
  Expenses:Car:Repair  $500.00
  Assets

If you don’t know what your monthly expenses are for individual categories following command that will report your monthly average might help you:

ledger bal --monthly --average expenses

Keep in mind though that in order to get accurate estimates you need to be keeping ledger for some time.

After you define your periodic transactions in the ledger file, you create budget report by adding --budget to the command you would otherwise normally use. E.g., to check your monthly expenses compared to the budget, you would use:

ledger reg --budget --monthly ^expenses

Here’s a more restricted output of

$ ledger --budget --monthly -p "this year" reg rent
01/01/2020 - 31/01/2020            Expenses:Living:Rent         $-10.00     $-10.00
01/02/2020 - 29/02/2020            Expenses:Living:Rent          $14.00      $-4.00
01/03/2020 - 31/03/2020            Expenses:Living:Rent          $14.00      $-4.00

The first column with values tells you the difference between the budget and the actual amount spent. The second column is the final running balance and doesn’t provide much information when reporting on averages or against budget.

Examples

; Exchanging currencies in a single account
2020/04/24 * Exchange
  Revolut  €400.50 @ $0.92
  Revolut

; Paying lunch for your friend
2020/04/24 * Restaurant
  Expenses:Food:Lunches  $10
  Assets:Reimbursements  $9.50 ; Payee: My Friend
  Assets:Cash

; Getting paid back for the lunch
11/02/2020 * My Friend
  Assets:Checking  $9.50
  Assets:Reimbursements  ; Payee: My Friend

Summary

It might feel demanding and time-consuming to keep a financial journal, but the benefits overweight all the negatives. Keeping a journal provides you with enormous insight into your financial state and helps you optimize. If you want to keep your finances at check or if you are just interested in what you spend the most on, Ledger is the right tool for you.

Owning Your Own Shadow

matousdzivjak@gmail.com (Matouš Dzivjak) — Sun, 02 Feb 2020 00:00:00 +0000

TODO

How To Fail at Almost Everything And Still Win Big

matousdzivjak@gmail.com (Matouš Dzivjak) — Mon, 20 Jan 2020 00:00:00 +0000

Sense of Style

matousdzivjak@gmail.com (Matouš Dzivjak) — Sat, 04 Jan 2020 00:00:00 +0000

TODO

Factfulness

matousdzivjak@gmail.com (Matouš Dzivjak) — Fri, 03 Jan 2020 00:00:00 +0000

Notes

Gap Instinct
- tendency to divide things into two distinct and often conflicting groups with an imagined gap between them
- liberals vs. republicans, us vs. them, etc.
- beware when gap is mentioned and keep in mind that majority usually lies in the middle
- don’t compare averages, consider the spread as well
- beware when extremes are being compared
Negativity Instinct
- tendency to notice the bad more than the good
- distinguish better and bad, think can be bad but getting better
- good news == no news, good news are often not being reported
- gradual improvement == no news, gradual improvement is often not reported
Straight Line Instinct
- tendency to assume that a line will just continue straight and ignoring that such lines are rare in reality.
- also expanded in the book Growth by Vaclav Smil, growth curves usually follow the S shape
Fear Instinct
- tendency to pay more attention to frightening things
- that’s why people prefer news about mass shootings, murders, and other misfortune while ignore positive development
- risk = danger * exposure
Size Instinct
- tendency to get things out of proportion, or misjudge the size of things
- e.g. irrational feat of immigrants while the actual numbers are low, ties into the Feat Instinct
- always search for the context of the numbers, single numbers on their own are often misleading
- amounts and rates often tell very different stories
Generalization Instinct
- tendency to mistakenly group together things, people, or countries that are actually very different
- look for differencies within groups, look for similarities across groups
- majority can mean anything from 51% to 99%
- vivis images are easy to recall but they might be exception, no the rule
Destiny Instinct
- idea that innate characteristics determine the destinies of people, countries, religions, or cultures
- tendency to think that things are as they are because of inescapable reasons
- keep track of gradual improvements, update your knowledge
- if you need a reminder of how things were, talk to your grandpa
Single Perspective
- tendency to focus on a single cause or perspective when it comes to understanding the world
- e.g. forming our worldview by relying on the media or our social bubble
- test your ideas, limit assumption of your experise and be humble
- Hammer and nails - if you are good with a tool, you might be prone to overuse it, not one tool is good for everything
- beware of simple ideas and simple solutions, world is never simple
Blame Instinct
- tendency to find a clear, simple reason for why something bad has happened
- look for causes, not villains
- look for systems, not heroes
Urgency Instinct
- tendency to take immediate action in the face of perceived imminent danger, and in doing so, amplifying our other instincts
- used often in marketing
- take a breath and time, don’t rush your decisions, evaluate
- insist on the data
- beware of predictions, future is uncertain ("this stock can’t go tits up"¹)

https://idioms.thefreedictionary.com/go+tits+up ↩︎

Enlightenment Now

matousdzivjak@gmail.com (Matouš Dzivjak) — Thu, 02 Jan 2020 00:00:00 +0000

In 15 extensive chapters Steven Pinker makes a case for reason, science and humanism. Each chapter describes a measure of civilization well-being, be it life expectancy, quality of life, safety, education and more. Each chapter is supported with ton of data digested to memorable and compelling form, with plenty of charts and graphs that make it ever so easier to make sense of otherwise unrelated numbers.

Enlightenment Now is optimistic, light, and brilliant read showing the progress of our species throughout the decades, explaining why we are instead drawn to the pessimism and how we choose to believe that the world is getting worse by day. In certain ways this book is similar to Factfulness by Hans Rosling but emphasizing more the data and context to back up the signs of progress in each chapter. Enlightenment Now left me knowing, that the world is getting better even though it doesn’t always have to feel this way.

Business Adventures

matousdzivjak@gmail.com (Matouš Dzivjak) — Wed, 01 Jan 2020 00:00:00 +0000

Twelve tales of success, failure, and lessons learned in the business word in the last century. Written in captive and thrilling style that would hold even for Netflix miniseries.

A briefer History of Time

matousdzivjak@gmail.com (Matouš Dzivjak) — Wed, 04 Dec 2019 00:00:00 +0000

Simple, yet not stupid introduction to physics, and the universe that will leave you contemplating the complexity of the world from the tiniest quarks to super massive black holes. A brief History of Time is fast and easy read graspable to anyone with at least some knowledge of basic high school physics.

About

matousdzivjak@gmail.com (Matouš Dzivjak) — Mon, 01 Jan 0001 00:00:00 +0000

Hi, I’m Matouš Dzivjak!

I work as a Staff Engineer at SumUp and do a lot of sports. The rest of my free time is spent on coding, friends, reading, cooking, and other stuff. This blog was started in 2019 to force myself into writing more and to have a place where I could share my thoughts and knowledge. Please take this whole site with grain of salt as my english is far from perfect, and I feel like creating a coherent piece of writing is still impossible task for me (I am working on it though).

Career

Staff Engineer @ SumUp, 5/2025 - now

Senior Software Engineer @ SumUp, 6/2021 - 5/2025

Working in the Platform Tribe - Identity Squad along with a 10 incredible teammates. The IAM (Identity & Access Management) team had its inception 2 months before I joined SumUp and we scale from 3 people drowning in incidents and work to 10 people in 2022 drowning only in work.

In the 3 years so far I have contributed to building a company-wide SSO (Single Sign-On) based on OIDC and OAuth2, authored a generic MFA (Multi-Factor Authentication) API that support recovery codes, TOTPs, SMS OTPs, webauthn credentials, and bootstrapped ReBAC-based access control system from RFC, to proof-of-concept, load testing, to adoption and general availability. Apart from the IAM related responsibilities I spend time on our public APIs, running an RFC forum, and Go and Rust guild.

Backend Developer @ Kiwi.com, 2/2019 - 5/2021

At Kiwi our team’s responsibility was developing core infrastructure and services with speed and maintainability as the primary goal. Our services served thousands of requests per second and served as the base for the transportation search engine. During my time at Kiwi I grew my experience and knowledge thanks to awesome team and mentorship from other skilled people in the company.

My contributions included initiating gRPC adoption across the company, helping build internal Go packages for cross-team usage, and developing multiple internal core APIs supporting search search functionality serving 100M request every day.

DevOps and Technical Support for Ads Systems @ FTV Prima, 9/2018 - 1/2019

Technical support for online platform advertisement team. Helping with every possible task at hand, so mostly scripting and data pipelines.

Full-Stack Developer @ Techambition Ltd., 9/2017 - 5/2018

Full-stack developer (Node.js and React) of an online interactive tool for high school mathematics in a small startup.

Projects

I enjoy programming outside the work as well and have build and still maintain a few personal projects:

go-nanoid - Tiny Go package for generating URL friendly unique IDs.
Mnemoname - tiny Go utility for generating mnemonic names.
ezmail - easy CLI utility for sending emails from terminal useful for scripts and people that don’t want to set up the default mail command that saves credentials into secure enclave.
dzxcodes - this website, using the Hugo framework.
linkfix - a simple tool that helps you avoid the Link rot by reporting on no-longer working links in your files and suggesting replacements with Wayback Machine snapshots wherever possible.
newz - News aggregator inspired by HN and Reddit written in python.
godox - tool to extract specific comments from Go code based on keywords. Later integrated into the Golangci Lint.
gosmtp - Go implementation of full-featured, lightweight and RFC compliant SMTP server.

I also contribute to a few open source projects:

helix - A post-modern modal text editor written in Rust.
hydra - OpenID Certified™ OpenID Connect and OAuth Provider written in Go.

All

matousdzivjak@gmail.com (Matouš Dzivjak) — Mon, 01 Jan 0001 00:00:00 +0000

Etc.

matousdzivjak@gmail.com (Matouš Dzivjak) — Mon, 01 Jan 0001 00:00:00 +0000

I keep most of the other cool stuff in my wiki. Here’s distilled content that I thing might be of interest to anyone that stumbled upon this page.

Articles

I am big fan of long format investigative writing. If the author spends the time researching the topic and is able to assimilate accumulated knowledge into a coherent piece writing the topic stops being relevant. This list is longer than I originally intended but I read a lot and there’s just simply a lot of great articles worth mentioning:

The Clock Is Ticking - Inside the Worst U.S. Maritime Disaster in Decades by William Langewiesche
The White Darkness - A solitary journey across Antarctica - by David Gran
A Conspiracy To Kill IE6 - by Chris Zacharias
“There Is Definite Hanky-Panky Going On” - The Fantastically Profitable Mystery of the Trump Chaos Trades - by William D. Cohan
Dear Guy Who Just Made My Burrito - A Fictional Letter Written to a Fictional Person About a Real Struggle - oh yes, the famous burrito rant by Jack Dire
Leave No Soldier Behind - The Unsolved Mystery of the Soldier Who Died in the Watchtower - by William Langewiesche
The 10-Minute Mecca Stampede That Made History - William Langewiesche
How to Fairly Divide Talking Time
Thirty-six Thousand Feet Under the Sea - The explorers who set one of the last meaningful records on earth - by Ben Taub
50 Ideas That Changed My Life
The case of the 500-mile email

So many articles by William Langewiesche…

I will be fully honest here, absolutely anything by William Langewiesche is a pure masterpiece. If you love investigative, thrilling writing go ahead and read all Williams articles on Vanityfair. Disclaimer, you will want more!

A Collection of Unmitigated Pedantry by Dr. Bret C. Devereaux.
Alex Danco
Alexey Guzey
Amos
Arun Venkatesan, product designer and engineer with visually stunning blog posts and a lot of interesting work.
Avery Pennarun, the Tailscale CEO.
Bartosz Ciechanowski, interactive long form deep dives on engineering topics such as lenses, GPS, etc.
Brandur Leach, engineer at Crunchy Data, previously at Stripe and Heroku. This site takes a lot of inspiration from there.
Charity Majors - Honeycomb CEO
Christine Dodrill (Xe Iaso)
Chromakode (Max Goodman from xkcd, previously at Reddit)
Computers Are Bad by J. B. Crawford
Connor Bär
Danluu
Fabien Sanglard
Gwern Branwen
Jim Fisher
Jose Luis Ricon
Julia Evans - frequent smaller blog posts diving into various technical topics with comicstrips and wit
Julian D. A. Wiseman
Kris Machowski
Lesswrong
Lucas F. Costa
Nikita Voloboev, not a blog per se
Patrick Collison
Patrick McKenzie and his Bits about Money - a weekly newsletter on the intersection of tech and finance.
Paul Graham
Paul Stamatiou
Sandy Maguire
Scott Alexander’s Slate Star Codes, newly also Astral Codes Ten
Stephen Diehl
Steve Francia
Tim Bray
Tom MacWright
Tynan
Vitalik Buterin
Werner Vogels (All Things Distributed)
Will Larson
Work In Progress

Quotes

I am most likely destined for average life, which is completely fine. If you zoom out further and it becomes pretty hard to view this tiny spec of time we’ve given and all its trappings as anything more than ridiculous. You could become the most famous person in all of human history, build empires, construct massive monuments to your achievement, etch your damn face into the earth with a laser in space… and you’d still have just as much importance, in the scale of time and space, as every human that ever lived. Zero.¹

Philosophy

I am pragmatic optimist, ISTJ-A (Logistician) personality type according to Myers–Briggs Type Indicator.

To greater or lesser extend I identify with following philosophies:

Stoicism

The core teachings of Stoicism focus on the development of self-control and resilience in the face of life’s difficulties, and emphasize the importance of living in accordance with reason. Stoics believe that the key to a happy and fulfilling life is to focus on what is within our control, and to cultivate inner peace by accepting the things that are outside our control. They also believe in living a virtuous life, and see wisdom, justice, courage, and temperance as the four cardinal virtues.

https://www.reddit.com/r/AskReddit/comments/upyafq/comment/i8ol1b3/ ↩︎

Gear

matousdzivjak@gmail.com (Matouš Dzivjak) — Mon, 01 Jan 0001 00:00:00 +0000

Software

Terminal

Ghostty is my current terminal of choice. I went through Hyper, iTerm2, Kitty, and Wezterm before. Each time sacrificing bit of the features (that I didn’t use anyway) in favor of speed. Kitty, Wezterm, and Ghostty both seem on par in performance and I don’t have strong preference for one versus the others. At the moment, it’s Ghostty, in the future, I might go back to one of the others.

One underestimated factor of programming comfort are fonts. Good fonts strike the right balance of legibility, glyphs, and line-height. I have been using Berkeley Mono Typeface since its release, initially doubting whether paying for a font is a justifiable endeavor but it brings me tiny bit of joy whenever I open my terminal ever since.

Shell

I run Fish shell nowadays, it used to be Zsh and Oh My Zsh prior to that. The only plugin that I use is fzf.fish for history search. For prompt, I use minimal configuration of Starship prompt (directory and git information).

Editor

Screenshot of my editor as of the writing of this page.

Helix for almost everything, sometimes I spin up VS Code for a specific task. Last I remember it was for a multiline search and replace across a whole project (I couldn’t wrap my head around ast-grep at that time but got better hand of it since).

In university we had free licenses for JetBrain products and I used those when I started programming. For editing in terminal I would use Nano and avoid it like the plague. As I needed to edit more and more configuration files and sometimes work remotely I decided to learn working with Vim in February 2021. The learning curve is indeed steep but there’s certain level of satisfaction in taming the beast. Around that time LSP and Tree-Sitter were becoming the norm, enabling the full IDE experience in Vim at a cost of 600 lines long configuration file.

As with other tools, I started looking into simplifying the setup. I ditched a few plugins, removed all unnecessary configuration, and downsized by Neovim config file to half. That is, until I found Helix.

Helix provides similar experience to Vim with one major twist. While in Vim you start with action followed by motion (e.g. d3w to delete 3 words) Helix follows selection -> action paradigm inspired by Kakoune (if you never header of it, don’t worry, I did neither until reading more about Helix). It’s striking difference from Vim that takes time to get used to but comes naturally afterward. Second large difference is first-class support for multi-cursor. Where in Vim you would substitute using the %s/SEARCH/REPLACE/g command in Helix you select the text (e.g. % for whole file), select the pattern in the selection (e.g. s followed by the term you are searching for), by confirming the selection you create multiple individual cursor, and you can edit them all at once.

Nothing can be perfect though, development of Helix is moving at a slow pace with features such as plugin support taking years to make it into upstream. On the other hand, the slowness reduces feature creep and contributes to a clean codebase.

At the moment I am using the Modus Vivendi. A accessible theme, conforming with the highest standard for color contrast between background and foreground values (WCAG AAA) theme by Protesilaos Stavrou originally built for GNU Emacs.

Browser

After full circle, going from Firefox to Safari and later to Arc I am back at the beginning using Firefox as my primary desktop browser. There’s not much to it other than it works and it doesn’t get into my way.

Raycast

Raycast launcher is one of my essentials. I started with Alfred but didn’t like its UI and the way of writing extensions. It replaced a lot of other apps I previously depended on. Right now, it’s free for personal use which I expect to change at one point in the future but I am willing to pay for it. My only hope is that their model won’t be subscription based.

iA Writer

For writing posts for this blog and managing wiki.dzx.cz I use iA Writer. It’s an exceptionally well built writing software that helps me write. Built-in syntax highlight and style checking means one can focus on the content and iA Writer takes care of typos, common clichés, or redundancies.

Tools

HTTPie for HTTP
amber for search and replace
bat - cat alternative with colors and more
biff for date-time handling on command line
codex for running coding agents in terminal
dive for exploring docker images
doggo as a DNS client
dua to view disk space usage and delete unwanted data
eza modern alternative to ls
fd for finding files
fzf
git for version control obviously.
htop - interactive process viewer
hugo for static websites
imagemagick to manipulate, resize, and convert images
jq for JSON
k9s for managing kubernetes stuff
kubectx to switch between kube contexts
neofetch for fun
ouch for painless compression and decompression in the terminal
pandoc for documents and markdown, convert anything to anything
pgcli as a better alternative to the default psql
rg for code search
rsync for synchronization between machines
trash to not shoot myself in the leg when running rm
worktrunk for Git worktree management for parallel AI agent workflows
zoxide as a faster cd

Apps

1Password for passwords management
IINA for videos
Ice - a menu bar manager for MacOS to keep it nice and tidy.
Itsycal - tiny calendar for menu bar
Maccy - clipboard manager
balenaEtcher for flashing OS images to SD crds & USB driver
devtoys various developer tools for converting formats, images, and much more. Currently testing as a replacement for boop.

Mac Setup

Other

Wallpapers: OS9 Walppapers by Arun

Hardware

Apple MacBook Pro
iPhone 13 mini. I was split on whether to buy 13 or 13 mini when my trusty iPhone 7 stopped working. After some back and forth the decision was made to opt for the smaller model. It’s a phone and does the things that all other phones do. It stays charged throughout the day (the previous one didn’t), takes great pictures (the limit is currently my artistic sense, not the phone), can navigate me wherever I need.
AirPods 3rd generation. For a long time I refrained from buying expensive-ish wireless headphones. I loved the basic Apple airpods that used to be inlcuded in the box. When I broke the last ones that I got with my iphone 7 I switched to cheap Seinheisser XXX, the reasonale being that I will eventually leave them in a pocket of my running shorts and wash them. Those were only for sports and at work I used their bigger sibling . Eventually, when iPods 3 came out, I decided to give them a shot to see how they compare to their wired predecessors that I held so dear and it was a great decision. I can’t be bothered by wires again, ever. The sounds quality is stellar compared to what I had before and the Airpods already survived a few beatings (dropped them second week after purchase on a bike at 40 km/h) which is another big plus. For me they strike nice balance between simplicity, sound quality, and price and I most likely won’t be migrating to anything else anytime soon.

Keyboard

Typing on HHKB Pro Hybrid since 2025. The price tag made me reluctant to press the “Order” button but hey, I spend good part of the day programming or writing documents, and good keyboard brings me a joy. I was also afraid of the different layout (no fn key and ctrl in place of caps lock) but it took a day to get used to and in the end feels like significant ergonomics gain. Furthermore, HHKB uses Topre switches, unparalleled by any other keyboard I have had before.

Everyday

The Bag

Currently I use Thule Aion 40l as my every day carry. It’s big, sturdy, ideal when you want to bring clothes and shoes to go for a run after work and still buy the groceries on your way home. 40l initially seemed like an excesive volume for an every-day back pack but now I would hardly go for anything smaller.

Previously I used The Backpack Pro by Db which wasn’t bad but I had my complains. Thule was definitely an improvement although the number of internal compartements seems to be excessive in comparison to Db. On the other hand, the main pocket doesn’t open on it’s own when heavily loaded.

Everyday carry

Book. I Always carry at least one around¹, most of the time non-fiction books about software engineering, economics, statistics, or thinking. Sometimes I also read fiction but I tend to get very excited and hooked by the plot and the books don’t spend more than 3 days in my bag.
Tech Kit by Bellroy. I would consider this an unnecessary luxury but it works fine and I hope it will last for a long time. As a bonus, it also looks good.
TriggerPoint MBX and MobiPoint massage balls. Perfect small companions for recovery. Sometimes I use the MobiPoint to massage my feet even at work, and when needed, it can be used to apply pressure to verious stiff areas. Works like a charm.
Microfiber cloth to clean my glasses.
Screen wipes to clean my laptop screen.
Humangear spork in case I bring a food with me that can’t be eaten using the hand. In full honestly, all I really need is a spoon but I couln’t find a nice travel spoon so spork it is.
Nalgene 1l bottle to keep hydratated.
Landgarten Chocolate Fruits bio organic chocolate + fruite snack. I like raspberry and ginger the most. Also, the packages are quite small so it never happens that you eat too much.
100% Konnor sunglasses. I wear perscription glasses most the time and when deciding between seeing well versus being shileded from sun I opt for the former rather than later. Maybe one day I will get into the habit of using contact lenses also when not doing sports and the sunglasses will come in handy.
Curaprox Travel Set in case I ever forget my hygiene kit or get stuck with just my bag. The forgot part happens more frequently than I would like to admit. I haven’t used the kit yet, which just confirms the rule of it won’t happen if you are prepared.²
Moleskin Hard Cover A4 notebook
Aesop Resurrection Aromatique Hand Balm
Fisherman’s Friend mints for fresh breath. Most of the time the Raspberry flavour.

Sports

Some notes after a few years of doing quite a few sports:

When switching shoes (doesn’t matter if running or cycling), don’t go all in but alternate with your old shoes for at least first 2 weeks. Took me one heel inflammation and one knee inflammation to learn my lesson.
Sadly, price correlates with quality and good gear costs money. Ideally have friends that work in the industry and can get you discounts or tips at least (easier said than done).
If something works for you (e.g. certain brand of shoes fits you well) there’s no reason to experiment, usually that ends with more harm than good.

Running

I tend to keep running shoes for 600km - 1000km depending on their condition.

Clothing:

Soar Run Trousers, merino wool-lined trousers for cold weather.
Lululemon Surge Lined Short, shorts for any other weather.
Ciele M RCDTShirt – Elite, race t-shirt.
Ciele M DBSShort – Elite, race shorts for races up to the marathon distance.

Shoes:

Retired

On Running Cloudflow
Saucony Triumph 18
Mizuno Wave Rider 25
Saucony Kinvara 12, favourite
Saucony Endorphin Pro 2, favourite
Nike Zoom Fly 3, good shoe but narrow toe box and it lost the springiness really fast)

Clothing

I am slowly iterating towards have a few brands that have consistently good products that I like. In general I aim for brands with good reputation³ ⁴ even if that means paying premium. My woredrobe consistent mostly of plain, logo-less clothing

T-shirts

All plain in tame colors, from Asket, Zagh (a Czech brand), Pangaia, and ocassionally Zara. Recently I am a fan of the oversized and skater fit.

Pants

All my pants at the moment are from Lululemon and specifically two of their models, the ABC Slim-Fit Pant and Commission Slim-Fit Pant. I wear size 32" and they are the best fit I have found so far. Event he slim-fit cut fits well for figures with larger quads and don’t restrict the movement. I have different colors on rotation and for the hot some weather wear the WovenAir version with perforated fabric.

My friends will know that at least one usually means around 5 with the completely invalid argument behind it being “In case I finished one, I want to have a backup”. On the other hand, my bag is sufficiently large to fit them all, it’s only manifesting on the weight of it. ↩︎
Preparedness Paradox ↩︎
Patagonia founder just donated the entire company, worth $3 billion, to fight climate change ↩︎
Asket - Transparency ↩︎