kopi

A simple, immutable, 100% asynchronous programming language.

What started out as an exercise turned into a fully functional (but small) language. Kopi has a Haskell/ML/Scala style (minimal) syntax, behaves kind of like a LISP, and is interpreted in JavaScript. It has coroutines, and supports sevaral literal syntaxes (array, map). Many languages have been the inspiration for Kopi and its functions, either directly or indirectly: JavaScript, Dylan, SmallTalk, Io, Magpie, Scala, Go, Erlang, Scheme, Clojure, Racket, Ruby, Python, Julia, Idris, Haskell, Elm, PowerShell... there's probably more.

More details can be found here:

https://docs.google.com/presentation/d/1NtJtgIilqQv2XBoCmybcQU_IsEcylMOcLYXkgB5dQoM/edit?usp=sharing

Also check out the github Wiki https://github.com/mikeaustin/kopi/wiki, now with more examples and future features, and github Discussions https://github.com/mikeaustin/kopi/discussions if you're interested in talking about Kopi.

There are some code samples here and in the Wiki, but if you want to see code used for testing, check out the samples in the test folder: https://github.com/mikeaustin/kopi/tree/master/packages/kopi/test.

NOTE: Kopi is still in the experimental phase. Lots of things are changing, and new functionality is being added. It's not ready to be used in production environments, but please try it out, experiment with it, and have fun!

There are no keywords

'match' is simply a function, and pattern matching is just an n-tuple of anonymous functions.

factorial = n => match n (
  0 => 1
  n => n * (factorial n - 1)
)

print (factorial 170)

There is no mutation

Shared mutable data is evil, but some impure functions such as 'print' and 'random' are handy.

x = 1
f = () => x

x = "hi"
print (f (), x)

> (1, "hi")

No more async awaits

'input' simply waits for user input and resolves as an argument to 'match'. 'sleep' does the same.

match (input "Amount?") (
  "0" => print "> Zero"
   n  => sleep n
)

(sleep 1) + (sleep 1)

Other examples

1..2, "a".."z" | map (a, b) => a, b

1..5 | map () => sleep 1

1..3 | map 'toString

coroutine = spawn () => {
  loop = () => {
    yield x => x * x
    loop ()
  }
  loop ()
}

send coroutine 5  # prints '25'

Installation and running tests

Install the project

> git clone https://github.com/mikeaustin/kopi.git
> cd kopi/packages/kopi
> npm install

To start the REPL

> npm start

To run a specific test

> npm start test/basics.kopi

To run all tests

> npm test