lift.js is a compact monad opinionated javascript library. It implements Just (Identity), Maybe, Valid (Validation) and a nice Monad factory. The unit comes with a lift function so you can add functionnality later in code to your monad. It's ment to be flexible and simple to use. It's written with es6 so it's less than 100 lines.
npm install liftjs
yarn add liftjs
https://github.com/atomable/lift.js
All the following work, pick your demon. lift.js can be required directly for es next project or you can use the lift-min.js for all legacy applications.
var lift = require('liftjs');
const lift = require('liftjs');
import lift from 'liftjs';
import { Monad, Just, Maybe, Valid, Curry } from 'liftjs';Monad(modifier[monad, value]: null) : unit
const Person = Monad();
const person = Person({ firstname: 'Bill', lastname: 'Murray' });
// with a modifier
const doubleIt = Monad((monad, value) => {
monad.double = value * 2;
});
const two = doubleIt(2);
two.double();
// 4With the lift function you can add function at any time on the monads.
Monad[A].lift[name, func[A] : Monad[A]];
const justWithLog = Just(5);
Just.lift('log', console.log);
justWithLog.log();
// console> 5You can also use it on your custom monads.
const Person = Monad();
const person = Person({ firstname: 'Bill', lastname: 'Murray' });
const FullName = Monad();
Person.lift('compose', person => FullName(`${person.firstname}, ${person.lastname}`));
person.compose().run(console.log);
// console> Bill, MurrayJust is an implementaion of the Identity monad. It's called Just because an 8 character variable is just too long.
The folowing function are available on Just, Maybe, Valid.
Monad[A].bind[func[A] : Monad[B], args] : Monad[B]
const justWithValue = Just(5).bind((value)=> Just(value));
// Just[5]Monad[A].of[B] : Monad[B]
const justWithValue = Just(5).of(6);
// Just[6]
const justWithValue = Just(5).of(Just(6));
// Just[6]Monad[A].get[] : A
const value = Just(5).get();
// 5Monad[A].map[func[A] : B ] : Monad[B]
const justWithValue = Just(7).map(value => value * 2);
// Just[14]Monad[Monad[A]].join[] : Monad[A]
const justWithValue = Just(Just(5)).join()
// Just[5]Monad[A].toMaybe[] : Maybe[A]
const maybeWithValue = Just(5).toMaybe();
// Maybe[5]Monad[A].run[func[A] : null]: Monad[A]
Just(5).run(value => console.log(value));
// console> 5Maybe(A) : Maybe[A]
const maybeWithoutValue = Maybe()
// Maybe[]
const maybeWithValue = Maybe(2)
// Maybe[2]
const maybeWithoutValue = Maybe(undefined)
// Maybe[]
const maybeWithoutValue = Maybe(null)
// Maybe[]Maybe[A].isNothing[] : boolean
const value = Maybe(5).isNothing();
// false
const value = Maybe(5).n();
// falseMaybe[A].is[] : boolean
const value = Maybe(5).is();
// true
const value = Maybe(5).i();
// trueMaybe[A].or[B] : A or B
const maybeWithValue = Maybe().or(15);
// 15Maybe[A].else[Monad[B]] : Maybe[A] or Monad[B]
const maybeWithValue = Maybe(5).else(Maybe(15));
// Maybe[5]
const maybeWithValue = Maybe().e(Just(15));
// Just[15]IO(func[A]: B) : func[A] : IO[B]
const appleIO = IO((num) => num + ' apple');
appleIO(4);
appleIO.run();
// apple
const randomIO = IO(() => Math.random());
randomIO()
.run();
// 0.12701886093193782
const writeFile = IO((file, contents) => fs.writeFileSync(file, contents, 'UTF-8'));
randomIO('/file.json', JSON.strigify({ monads : 'are awesome' }));
.run();
// file is written to disk syncCurry is a factory that takes a function and returs a curried function.
Curry(func) : func
const curried = Curry((a, b) => a * b);
curried(3)(6);
// 18
Curry((a, b, c) => a + b + c)(1, 2, 3)
// 6I don't plan on adding all the typical monads to the library, if you feel one should be added you are welcome to make a pull request or to fork. I'm thinking of Free and List, but not sure yet. It will depend on what I use in my own projects.
Below are the things that I actually plan on doing. Soon.
- document
Valid - document
lift_valuefunction - document
methodfunction - add List monad
apfunction justJustandMaybe& tests- tests for lift functions
- 1.2.0 : I've changed the Maybe api qute a bit, orSome, orElse, none, are replaced.
Written and maintained by pre63.
Sponsored by atomable.
Based on Douglas Crockford MONAD.
Special thanks to Monet for the inspiration.