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.

Paradigm functional, lazy/non-strict, modular Simon 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 1990; 34 years ago Haskell 2010[1] / July 2010; 14 years ago Announced as Haskell 2014[2] static, strong, inferred Cross-platform `.hs`, `.lhs` haskell.org GHC, Hugs, NHC, JHC, Yhc, UHC Helium, Gofer

## Examples

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)
```

## Influence

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]

## References

1. Marlow, Simon (24 November 2009). "Announcing Haskell 2010" (Mailing list). Retrieved 12 March 2011. `{{cite mailing list}}`: Unknown parameter `|mailinglist=` ignored (help)
2. Lynagh, Ian (1 May 2013). "Haskell 2014" (Mailing list). Retrieved 9 October 2013. `{{cite mailing list}}`: Unknown parameter `|mailinglist=` ignored (help)
3. Chevalier, Tim (28 January 2008). "anybody can tell me the pronuncation of "haskell"?" (Mailing list). Retrieved 12 March 2011. `{{cite mailing list}}`: Unknown parameter `|mailinglist=` ignored (help)
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}}`: Cite journal requires `|journal=` (help)
9. Hudak et al. 2007, pp. 12-45–46.
10. Meijer, Erik (1 October 2009). "C9 Lectures: Dr. Erik Meijer – Functional Programming Fundamentals, Chapter 1 of 13". Channel 9. Microsoft. Archived from the original on 16 June 2012. Retrieved 9 February 2012.
11. Drobi, Sadek (4 March 2009). "Erik Meijer on LINQ". InfoQ. San Francisco: C4Media Inc. Retrieved 9 February 2012.
12. Hickey, Rich. "Clojure Bookshelf". Listmania!. Amazon.com. Retrieved 9 February 2012.
13. 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.
14. 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.
15. "Glossary of Terms and Jargon". Perl Foundation Perl 6 Wiki. The Perl Foundation. Archived from the original on 21 January 2012. Retrieved 9 February 2012.
16. Kuchling, A. M. "Functional Programming HOWTO". Python v2.7.2 documentation. Python Software Foundation. Retrieved 9 February 2012.
17. Fogus, Michael (6 August 2010). "MartinOdersky take(5) toList". Send More Paramedics. Retrieved 9 February 2012.