PureScript

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PureScript is an open source programming language created in 2013 by Phil Freeman.

Source code:

git clone https://github.com/purescript/purescript

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A strongly-typed language that compiles to JavaScript

PureScript website
PureScript Wikipedia page
PureScript is developed on GitHub and has 7,813 stars
PureScript docs
There are at least 5,443 PureScript repos on GitHub
file extensions for PureScript include purs
PureScript compiles to JavaScript
PureScript on Twitter
The Google BigQuery Public Dataset GitHub snapshot shows 382 users using PureScript in 826 repos on GitHub
There are 4 Project Euler users using PureScript
PureScript LSP implementation
GitHub supports syntax highlighting for PureScript
There is 1 Jupyter Kernel for PureScript
There is a central package repository for PureScript
Release Notes for PureScript

Example from the web:

import Prelude
import Effect.Console (log)

greet :: String -> String
greet name = "Hello, " <> name <> "!"

main = log (greet "World")

Example from hello-world:

module Main where

import Debug.Trace

main = trace "Hello World"

Example from Linguist:

module Control.Arrow where

import Data.Tuple

class Arrow a where
  arr :: forall b c. (b -> c) -> a b c
  first :: forall b c d. a b c -> a (Tuple b d) (Tuple c d)

instance arrowFunction :: Arrow (->) where
  arr f = f
  first f (Tuple b d) = Tuple (f b) d

second :: forall a b c d. (Category a, Arrow a) => a b c -> a (Tuple d b) (Tuple d c)
second f = arr swap >>> first f >>> arr swap

swap :: forall a b. Tuple a b -> Tuple b a
swap (Tuple x y) = Tuple y x

infixr 3 ***
infixr 3 &&&

(***) :: forall a b b' c c'. (Category a, Arrow a) => a b c -> a b' c' -> a (Tuple b b') (Tuple c c')
(***) f g = first f >>> second g

(&&&) :: forall a b b' c c'. (Category a, Arrow a) => a b c -> a b c' -> a b (Tuple c c')
(&&&) f g = arr (\b -> Tuple b b) >>> (f *** g)

class ArrowZero a where
  zeroArrow :: forall b c. a b c

infixr 5 <+>

class ArrowPlus a where
  (<+>) :: forall b c. a b c -> a b c -> a b c

Feature	Supported	Token	Example
Strings	✓	"	"Hello world"
MultiLine Comments	✓	{- -}	{- A comment -}
Line Comments	✓	--	-- A comment
Semantic Indentation	✓		-- https://github.com/purescript/documentation/blob/master/language/Syntax.md -- Syntax is whitespace sensitive. The general rule of thumb is that declarations which span multiple lines should be indented past the column on which they were first defined on their subsequent lines. foo = bar + baz
Doc comments	✓		-- https://github.com/purescript/documentation/blob/master/language/Syntax.md -- \| `bool` performs case analysis for the `Boolean` data type, like an `if` statement. bool :: forall a. Boolean -> a -> a -> a bool true x _ = x bool false _ x = x
Comments	✓

PureScript - Programming language

Language features

HackerNews discussions of PureScript