Haskell - Programming language

Haskell is an open source programming language created in 1990 by Paul Hudak and John Hughes.

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Haskell is a standardized, general-purpose purely functional programming language, with non-strict semantics and strong static typing. It is named after logician Haskell Curry. The latest standard of Haskell is Haskell 2010. Read more on Wikipedia...

Tags: programming language
There are at least 126,924 Haskell repos on GitHub
Early development of Haskell happened in Yale University and Chalmers University and Microsoft and University of Edinburgh
The Google BigQuery Public Dataset GitHub snapshot shows 13k users using Haskell in 30k repos on GitHub
Check out the 311 Haskell meetup groups on Meetup.com.
There are 7,098 Project Euler users using Haskell
In the 2021 StackOverflow developer survey Haskell programmers reported a median salary of $67,021. 2% of respondents reported using Haskell. 1,749 programmers reported using Haskell, and 3,453 said they wanted to use it
Explore Haskell snippets on Rosetta Code
Haskell on HOPL
Haskell appears in the TIOBE Index
Haskell Ubuntu package
Haskell LSP implementation
CodeMirror package for syntax highlighting Haskell
Pygments supports syntax highlighting for Haskell
GitHub supports syntax highlighting for Haskell
Haskell appears in the Quine Relay project
Learn Haskell on exercism.
There is 1 Jupyter Kernel for Haskell
There is a central package repository for Haskell
Indeed.com has 190 matches for "haskell developer".
haskell.org was registered in 1996
See also: (43 related languages) Clean, FP, HOPE, Irvine Dataflow, ISWIM, KRC, Lisp, Miranda, ML, Standard ML, Scheme, SISAL, Agda, C#, LINQ, Cayenne, Clojure, CoffeeScript, Curry, Elm, Epigram, F#, Frege, Hack, Idris, Java, LiveScript, Mercury, Raku, Python, Rust, Scala, Swift, Visual Basic .NET, C, C--, LLVM IR, OpenGL, JavaScript, Lazy ML, Pandoc, Cryptol, JVM
87 PLDB concepts link to Haskell: Ace Editor, Aith, Astatine, asterius-compiler, atomspace, attoparsec, badlanguage, Boomerang Decompiler, Bruijn, carp, carth, Civet, clash, cloc, Cryptol, Curly, Curry, Darcs Advanced Revision Control System, datafun, dex, Dhall, Differential Datalog, Đ, Egison, Elm, Encore, Enso, expresso, fay, Felix, Flare, forest-lang, fp, Frank, F*, Futhark, GHC, Gren, hakaru, hamler, harlan, haste, helium, Idris, JSON lambda, juvix, Kalyn, kei, keli, kima, kitlang, kitten, Koka, lambcalc, lamdu-editor, Lamdu, Lawvere, Ligo, Lucid, Luna, mal, Megaparsec, MLscript, monte, Mushroom, neut, Nit, Octune, oden, Pact, Pandoc, Parsec, Particles, plam, psyche-c, PureScript, Pygments, reflex-framework, Scrapscript, Simplicity, sixten, Slab, son, Topaz, UCL, Wasp, Z

Example from Compiler Explorer:

module Example where

sumOverArray :: [Int] -> Int
sumOverArray (x:xs) = x + sumOverArray xs
sumOverArray [] =  0

Example from Riju:

module Main where

main :: IO ()
main = putStrLn "Hello, world!"

Example from hello-world:

module Main where

main = putStrLn "Hello World"

Example from the Hello World Collection:

-- Hello World in Haskell
 
main = putStrLn "Hello World"

Example from Linguist:

import Data.Char

main :: IO ()
main = do
	let hello = "hello world"
	putStrLn $ map toUpper hello

Example from Wikipedia:

$ ghci
Prelude> import Data.Int
Prelude Data.Int> fromIntegral (32767 :: Int16) :: Int8
-1
Prelude Data.Int> fromInteger (2^64 :: Integer) :: Int32
0

Haskell Keywords

! ' '' - -< -<< -> :: ; <- , = => > ? # \* @ [|, |] \ \_ ` {, } {-, -} | ~ as case of class data family instance default deriving do forall foreign hiding if then else import infix infixl infixr let in mdo module newtype proc qualified rec type where

Language features

Feature	Supported	Example	Token
Standard Library	✓	main = putStrLn "Hello, World!"
Binary Literals	✓	-- 0[bB]_[01](_[01])*
Integers	✓	-- \d(_\d)
Floats	✓	-- 0[xX]_[\da-fA-F](_[\da-fA-F])_[pP][+-]?\d(_\d)
Hexadecimals	✓	-- 0[xX]_[\da-fA-F](_[\da-fA-F])*
Octals	✓	-- 0[oO]_[0-7](_[0-7])*
Conditionals	✓
Classes	✓
Case Sensitivity	✓
Print() Debugging	✓		putStrLn
Range Operator	✓
Function Composition	✓	foo = f . g
Line Comments	✓	-- A comment	--
Type Inference	✓
Semantic Indentation	✓
Operator Overloading	✓
File Imports	✓	import Data.Maybe import Mod as Foo import Mod (x,y, (+++)) import qualified Mod import Mod hiding (x,y,(+++)) import qualified Mod hiding (x,y)
Directives	✓	{-# INLINE foo #-}
Garbage Collection	✓
Pattern Matching	✓	fib 0 = 1 fib 1 = 1 fib n \| n >= 2 = fib (n-1) + fib (n-2)
Zippers	✓	-- https://wiki.haskell.org/Zipper_monad/TravelTree
MultiLine Comments	✓		{- -}
Comments	✓	-- a single line comment {- A multiline comment which can continue for many lines -}
Map Functions	✓	class Functor f where fmap :: (a -> b) -> f a -> f b (<$) :: a -> f b -> f a
Monad	✓	-- https://stackoverflow.com/questions/44965/what-is-a-monad parseExpr = parseString <\|> parseNumber parseString = do char '"' x <- many (noneOf "\"") char '"' return (StringValue x) parseNumber = do num <- many1 digit return (NumberValue (read num))
Typed Holes	✓	-- Found hole `_' with type f (Free f b)
Runtime Guards	✓	f x \| x > 0 = 1 \| otherwise = 0
Strings	✓	"hello world"	"
Case Insensitive Identifiers	X