Added

Language

• Default argument values have been introduced to make it easier to implement optional arguments.
  • For example, instead of:

    f = |a, b|
      a + (b or 42)

    You can write:

    f = |a, b = 42|
      a + b

• Wildcard imports have been added to make it easier to work with modules with lots of exported values.

  • from number import *
    assert_eq pi * 2, tau

• When calling a function, arguments can be now be unpacked at the call site.
  #418

  • f = |a, b, c| a + b + c
    x = 1, 2, 3
    f x...
    #: 6

• A power operator ^ has been added for exponentiation operations, replacing number.pow.

  • x = 2 ^ 3
    #: 8
    x ^= 2
    #: 64

• Number literals can now include underscores.
  #399

  • x = 1_000_000
    y = 0xff_aa_bb

• Interpolated values can now be formatted with alternative representations.

  • print '{15:b}'
    #: 1111

  • The @debug metakey has been added to allow for additional debug information to be provided when formatting an object as a string.
• Values in lists or tuples definitions can now be omitted, with null being used to fill the gaps.

  • x = [1, , 3, , 5]
    #: [1, null, 3, null, 5]

• export can now take any iterable that yields key/value pairs.

  • export (1..=3).each |i| 'generated_{i}', i
    generated_3
    #: 3

• Ranges can now be indexed by number.

  • r = 100..200
    r[50]
    #: 150

• Overridden operator improvements
  • Objects can now define how arithmetic operations should behave when the object is on the RHS of an expression.
    • Overridden operators define how the object on the right-hand side of an operation should behave via the @r+, @r-, @r*, @r/, @r^, and @r% metakeys.
    • If the LHS value doesn't implement the operation, then the RHS value is checked for an available implementation.
  • != now derives its result by default from @== if it's implemented.
  • If @< and @== are implemented, then the other comparison operators are now derived automatically by default.

API

• koto_serialize has been replaced by koto_serde, which provides more complete support for converting between Koto values and types that implement serde::Deserialize and Serialize.
  • Types that implement Deserialize can be built from a KValue using from_koto_value.
  • Types that implement Serialize can be converted into a KValue using to_koto_value.
  • koto_serde is exported from koto as koto::serde when the serde feature is enabled.
• KotoObject has been extended with _rhs functions to support arithmetic operations where the object can appear on the right-hand side of the expression.
• Koto::call_exported_function has been added.
• Compiler::compile_ast has been added, useful for tools that want to work with the AST after checking that it compiles correctly.
• DisplayContext::debug_enabled has been added to allow native objects to provide additional debug information when KotoObject::display is called.
• KMap::remove and remove_path have been added.
  • See the prelude_value_remove.rs example for motivation.
• koto_parser now has an error_ast feature, which causes the parser to include the incomplete AST in koto_parser::Error when an error is an encountered.

Core Library

• New functions:
  • iterator.advance
  • string.strip_prefix / string.strip_suffix
  • string.trim_start / string.trim_end
    • string.trim now also accepts a pattern to match against.
• koto.unimplemented has been added to allow overridden left-hand side arithmetic operators to defer to right-hand side implementations.

CLI

• The CLI now has a --format argument that formats Koto scripts.
  • If a script path is provided then the file will be formatted in place, otherwise the script will be read from stdin and the formatted version will be written to stdout.
• The REPL now supports tab completion for variables and help searches.

Changed

Language

• Empty tuples are now created with ().
  • The previous empty-tuple syntax (,) now evaluates as a single-element tuple that contains null.
• Calls to Koto functions with the incorrect number of arguments will now throw an error.
  • Default values should be provided for optional arguments.
  • Variadic arguments should be used to capture additional arguments.
• Commas inside container definitions that were previously parsed as call arguments or inline function bodies are now more consistently parsed as entry separators.
  • [foo x, bar y] is now parsed as [foo(x), bar(y)], not [foo(x, bar(y))].
  • This allows functions to be more easily defined inside containers.
    • {square: |x| x ^ 2, cube: |x| x ^ 3} would have previously triggered a parsing error.
  • Inline function bodies that return tuples now require parentheses.
    • {swap: |a, b| b, a} should now written as {swap: |a, b| (b, a)}
  • Parentheses-free calls with multiple arguments that were wrapped in parentheses will need to be adjusted.
    • (foo 1, 2, 3) will now be parsed as (foo(1), 2, 3),
      and should be rewritten as foo(1, 2, 3).
• The -> pipe operator now inserts the piped value as the first argument to the call to the right of the pipe, instead of as the last argument.
  • This makes it easier to build pipelines with functions that treat the first argument as the subject of the operations, like instance functions.

    'hello!'
      -> string.to_uppercase
      -> string.repeat 3 # Previously this would have failed due to the arguments being out of order
    #: HELLO!HELLO!HELLO!

• Maps that implement @type now have their type included by default when rendering the map as a string. #478
• Integer arithmetic operations now wrap when overflowing the boundaries of the 64-bit signed range.

Core Library

• The argument order for the bounded version of iterator.generate has been swapped to make it consistent with the bounded version of iterator.repeat.
  • E.g. Instead of iterator.generate(3, f) you should write iterator.generate(f, 3).
• iterator.skip now skips when the iterator is advanced instead of immediately when skip is called.
• koto.args has been moved to os.args.

Extra Libs

• The random library now uses xoshiro256++ as its default random generator.
  • This is a faster and simpler algorithm than the previously used ChaCha8.
  • Seeded sequences will now be stable in future updates.

API

• Koto::run now takes a chunk argument instead of caching the output of Koto::compile.
• The vm argument has been removed from KotoObject::negate.

CLI

• The CLI is now built with extra optimizations by default, resulting in a faster binary at the expense of longer build times.
• Ctrl+C in the REPL now clears the line rather than exiting.

Removed

Core Library

• koto.exports has been removed.
  • export now accepts any iterable value which provides support for exporting generated keys.
• number.pow has been removed in favour of the ^ operator.

Fixed

Language

• Compound assignments in parenthesized comparisons are now evaluated correctly.
  • E.g. x = [0]; (x[0] += 1) == 0 would previously evaluate to true.

Core Library

• Iterator adaptors can now be used as standalone functions.
  • E.g. for i, n in iterator.enumerate 'abc' would previously throw an error.

• Compound assignments in parenthesized comparisons are now evaluated correctly.
  • E.g. x = [0]; (x[0] += 1) == 0 would previously evaluate to true.
• The error message for iterator.repeat has been fixed.

What's Changed

• Fixed a crash when calling a native function directly from another native function (#413)
• Enabled optimizations for release builds (#406 and #414
• Extra PartialEq and PartialOrd impls for KString (#411)

What's Changed

• Allow iterator adaptors to be used as standalone functions by @irh in #404

Full Changelog: v0.15.0...v0.15.1

What's Changed

• The pipes created during parsing instead of lexing by @Tarbetu in #311
• Remove the @Not metakey by @irh in #313
• Reserve some keywords that might be needed in the future by @irh in #314
• Don't rely on \r\n line endings in tests when running on Windows by @irh in #316
• Various tweaks by @irh in #317
• API Improvements by @irh in #318
• docs: Fix readme for poetry example by @madskjeldgaard in #319
• AST Newtypes by @irh in #321
• AST improvements by @irh in #323
• Add PartialEq + Eq to StringSlice derives by @irh in #324
• Implement Display for MetaKeyId by @irh in #325
• Prevent exhausted generators causing a panic by @edenbynever in #326
• Various tweaks by @irh in #327
• Implementing Typed Variable Declarations by @Tarbetu in #322
• Implement type checks for let expressions by @irh in #329
• Implementing Type Hints of Let expressions for Wildcards by @Tarbetu in #330
• Various tweaks by @irh in #331
• Add support for adding type hints to functions by @irh in #332
• More type checks by @irh in #333
• Ensure that type checks respect an object's @base entry by @irh in #334
• Add multi-assignment-support to export by @irh in #335
• Various tweaks by @irh in #336
• Tweaks and Fixes by @irh in #337
• Fix span placement for IDs with type hints by @irh in #338
• Type hints for generators by @irh in #340
• Ensure that libs can be used with the rc build variant by @irh in #342
• Fix minor typo in docs by @JamesHallowell in #341
• Better Argument Error Message For String Module by @Tarbetu in #345
• Indexable maps by @irh in #346
• Simplify Rc build variant selection by @irh in #348
• Improve errors for calls with unexpected arguments by @irh in #350
• Don't crash when random.pick is called with empty input by @irh in #351
• Add a Callable type hint by @irh in #352
• Add docs for overloads of iterator.product/sum that take an initial value by @irh in #353
• Type-checked catch blocks by @irh in #354
• Add support for generic types in the derive macros by @irh in #355
• iterator.repeat improvements and string.repeat by @irh in #356
• Implement TryFrom<KValue> for some std types by @irh in #357
• Various tweaks by @irh in #358
• Inline strings by @irh in #359
• Rework the color module by @irh in #360
• Mutable indexing improvements by @irh in #361
• stdio improvements by @irh in #363
• Optional chaining by @irh in #364
• Parser improvements by @irh in #365
• Remove the @tests metakey by @irh in #366
• Add an @index_mut metakey by @irh in #367
• Allow space before colon in Maps by @unlessgames in #369
• Flexible map syntax followups by @irh in #370
• Update some dependencies by @irh in #371
• Wasm followups by @irh in #373
• Move koto/test/libs tests into their respective crates by @irh in #374
• script_path / script_dir improvements by @irh in #375
• Add random.shuffle by @irh in #376
• Add exported map keys to local scope by @irh in #377
• Introduce semicolons by @irh in #378
• Add os.command to support spawning child processes by @irh in #380
• Docs update by @irh in #381
• Fix loading previously declared variables in the REPL by @irh in #382
• Performance improvements by @irh in #385
• Fix function comparisons by @irh in #386
• Make the runtime single-threaded by default by @irh in #387
• Add Color.alpha and .set_alpha by @irh in #388
• Ensure result registers are set to null when a chain fails a null check by @irh in #389
• Add support for optional type hints by @irh in #390
• API improvements by @irh in #391
• Various tweaks by @irh in #392
• release prep by @irh in #393

New Contributors

• @madskjeldgaard made their first contribution in #319
• @edenbynever made their first contribution in #326
• @JamesHallowell made their first contribution in #341
• @unlessgames made their first contribution in #369

Full Changelog: v0.14.1...v0.15.0

What's Changed

• Ensure that libs can be used with the rc build variant by @irh in #343

Full Changelog: v0.14.0...v0.14.1