Haskell (programming language)

purely functional programming language

Haskell /ˈhæskəl/[3] is a purely functional programming language. It is named after Haskell Brooks Curry, a U.S. mathematician who contributed a lot to logic. Haskell is based on lambda calculus and uses the Greek letter lambda as its logo. The main implementations are the Glasgow Haskell Compiler (GHC), and Hugs, a Haskell interpreter.

Paradigmfunctional, lazy/non-strict, modular
Designed bySimon Peyton Jones, Lennart Augustsson, Dave Barton, Brian Boutel, Warren Burton, Joseph Fasel, Kevin Hammond, Ralf Hinze, Paul Hudak, John Hughes, Thomas Johnsson, Mark Jones, John Launchbury, Erik Meijer, John Peterson, Alastair Reid, Colin Runciman, Philip Wadler
First appeared1990; 31 years ago (1990)
Stable releaseHaskell 2010[1] / July 2010; 11 years ago (2010-07)
Preview releaseAnnounced as Haskell 2014[2]
Typing disciplinestatic, strong, inferred
Filename extensions.hs, .lhs
Major implementations
GHC, Hugs, NHC, JHC, Yhc, UHC
Helium, Gofer


The following is an example Hello World program in Haskell:

module Main where

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

One way to create an infinite list of Fibonacci numbers is this:[4]

fib n = fibs !! n
        where fibs = 0 : 1 : zipWith (+) fibs (tail fibs)


Haskell was influenced by many earlier programming languages. These were Clean, FP, Gofer, Hope and Hope+, Id, ISWIM, KRC, Lisp, Miranda, ML and Standard ML, Orwell, SASL, SISAL, and Scheme.[5]

Haskell itself has influenced many later programming languages, such as Agda,[6] Bluespec,[7] C++11/Concepts,[8] C#/LINQ,[9][10][11][12] Cayenne,[9] Clean,[9] Clojure,[13] CoffeeScript,[14] Curry,[9] F#,[15] Isabelle,[9] Java/Generics,[9] Mercury,[9] Perl 6,[16] Python,[9][17] Scala,[9][18] Visual Basic 9.0.[9][10]


  1. Marlow, Simon (24 November 2009). "Announcing Haskell 2010". Haskell mailing list. http://www.haskell.org/pipermail/haskell/2009-November/021750.html. Retrieved 12 March 2011. 
  2. Lynagh, Ian (1 May 2013). "Haskell 2014". Haskell-prime mailing list. http://www.haskell.org/pipermail/haskell-prime/2013-May/003825.html. Retrieved 9 October 2013. 
  3. Chevalier, Tim (28 January 2008). "anybody can tell me the pronuncation of "haskell"?". Haskell-cafe mailing list. http://www.haskell.org/pipermail/haskell-cafe/2008-January/038756.html. Retrieved 12 March 2011. 
  4. "The Fibonacci sequence". HaskellWiki. 2 August 2012. Retrieved 27 March 2013.
  5. Peyton Jones, Simon, ed. (2003). Haskell 98 Language and Libraries: The Revised Report. Cambridge University Press. p. xi. ISBN 0521826144.
  6. Norell, Ulf (2008). "Dependently Typed Programming in Agda" (PDF). Gothenburg: Chalmers University. Retrieved 9 February 2012.
  7. Hudak et al. 2007, p. 12-38,43.
  8. Stroustrup, Bjarne; Sutton, Andrew (2011). "Design of Concept Libraries for C++" (PDF). Archived from the original (PDF) on 2012-02-10. Retrieved 2013-11-01. Cite journal requires |journal= (help)
  9. 9.0 9.1 9.2 9.3 9.4 9.5 9.6 9.7 9.8 9.9 Hudak et al. 2007, pp. 12-45–46.
  10. 10.0 10.1 Meijer, Erik. "Confessions of a Used Programming Language Salesman: Getting the Masses Hooked on Haskell" (PDF). OOPSLA 2007.
  11. Meijer, Erik (1 October 2009). "C9 Lectures: Dr. Erik Meijer – Functional Programming Fundamentals, Chapter 1 of 13". Channel 9. Microsoft. Retrieved 9 February 2012.
  12. Drobi, Sadek (4 March 2009). "Erik Meijer on LINQ". InfoQ. QCon SF 2008: C4Media Inc. Retrieved 9 February 2012.CS1 maint: location (link)
  13. Hickey, Rich. "Clojure Bookshelf". Listmania!. Amazon.com. Retrieved 9 February 2012.
  14. Heller, Martin (18 October 2011). "Turn up your nose at Dart and smell the CoffeeScript". JavaWorld. InfoWorld. Archived from the original on 10 February 2012. Retrieved 9 February 2012.
  15. Syme, Don; Granicz, Adam; Cisternino, Antonio (2007). Expert F#. Apress. p. 2. F# also draws from Haskell particularly with regard to two advanced language features called sequence expressions and workflows.
  16. "Glossary of Terms and Jargon". Perl Foundation Perl 6 Wiki. The Perl Foundation. 28 February. Archived from the original on 21 January 2012. Retrieved 9 February 2012. Check date values in: |date= (help)
  17. Kuchling, A. M. "Functional Programming HOWTO". Python v2.7.2 documentation. Python Software Foundation. Retrieved 9 February 2012.
  18. Fogus, Michael (6 August 2010). "MartinOdersky take(5) toList". Send More Paramedics. Retrieved 9 February 2012.