   Link: alternate
   Link: license
   Link: canonical

                         Haskell (programming language)

   From Wikipedia, the free encyclopedia
   Jump to navigation Jump to search

                                    Haskell
   Logo of Haskell          
   Paradigm                 Purely functional                                 
                            Lennart Augustsson, Dave Barton, Brian Boutel,    
                            Warren Burton, Joseph Fasel, Kevin Hammond, Ralf  
   Designed by              Hinze, Paul Hudak, John Hughes, Thomas Johnsson,  
                            Mark Jones, Simon Peyton Jones, John Launchbury,  
                            Erik Meijer, John Peterson, Alastair Reid, Colin  
                            Runciman, Philip Wadler                           
   First appeared           1990; 32 years ago^[1]                            
   Link: mw-deduplicated-inline-style
   Stable release           Haskell 2010^[2] / July 2010; 11 years ago        
   Preview release          Haskell 2020 announced^[3]                        
   Typing discipline        Inferred, static, strong                          
   OS                       Cross-platform                                    
   Filename extensions      .hs, .lhs                                         
   Website                  www.haskell.org                                   
   Major implementations    
   GHC, Hugs, NHC, JHC, Yhc, UHC
   Dialects                 
   Helium, Gofer            
   Influenced by            
   Clean,^[4] FP,^[4] Gofer,^[4] Hope and Hope^+,^[4] Id,^[4] ISWIM,^[4]
   KRC,^[4] Lisp,^[4] Miranda,^[4] ML and Standard ML,^[4] Orwell, SASL,^[4]
   Scheme,^[4] SISAL^[4]    
   Influenced               
   Agda,^[5] Bluespec,^[6] C++11/Concepts,^[7] C#/LINQ,^[8]^[9]^[10]^[11]
   CAL,^[citation needed] Cayenne,^[8] Clean,^[8] Clojure,^[12]
   CoffeeScript,^[13] Curry,^[8] Elm, Epigram,^[citation needed] Escher,^[14]
   F#,^[15] Frege,^[16] Hack,^[17] Idris,^[18] Isabelle,^[8]
   Java/Generics,^[8] LiveScript,^[19] Mercury,^[8] Ωmega, PureScript,^[20]
   Python,^[8]^[21] Raku,^[22] Rust,^[23] Scala,^[8]^[24] Swift,^[25]
   Timber,^[26] Visual Basic 9.0^[8]^[9]

   Haskell (/ˈhæskəl/^[27]) is a general-purpose, statically-typed, purely
   functional programming language with type inference and lazy
   evaluation.^[28]^[29] Designed for teaching, research and industrial
   application, Haskell has pioneered a number of programming language
   features such as type classes, which enable type-safe operator
   overloading. Haskell's main implementation is the Glasgow Haskell Compiler
   (GHC). It is named after logician Haskell Curry.^[1]

   Haskell's semantics are historically based on those of the Miranda
   programming language, which served to focus the efforts of the initial
   Haskell working group.^[30] The last formal specification of the language
   was made in July 2010, while the development of GHC has expanded Haskell
   via language extensions. The next formal specification was planned for
   2020.^[3] On 29 October 2021 GHC2021 was released in GHC version
   9.2.1.^[31]

   Haskell is used in academia and industry.^[32]^[33]^[34] As of May 2021,
   Haskell was the 28th most popular programming language by Google searches
   for tutorials,^[35] and made up less than 1% of active users on the GitHub
   source code repository.^[36]

Contents

     * 1 History
          * 1.1 Haskell 1.0 to 1.4
          * 1.2 Haskell 98
          * 1.3 Haskell 2010
     * 2 Features
     * 3 Code examples
     * 4 Implementations
     * 5 Notable applications
          * 5.1 Industry
          * 5.2 Web
     * 6 Criticism
     * 7 Related languages
     * 8 Conferences and workshops
     * 9 References
     * 10 Further reading
     * 11 External links

History[edit]

   Following the release of Miranda by Research Software Ltd. in 1985,
   interest in lazy functional languages grew. By 1987, more than a dozen
   non-strict, purely functional programming languages existed. Miranda was
   the most widely used, but it was proprietary software. At the conference
   on Functional Programming Languages and Computer Architecture (FPCA '87)
   in Portland, Oregon, there was a strong consensus that a committee be
   formed to define an open standard for such languages. The committee's
   purpose was to consolidate existing functional languages into a common one
   to serve as a basis for future research in functional-language
   design.^[37]

  Haskell 1.0 to 1.4[edit]

   Type classes, which enable type-safe operator overloading, were first
   proposed by Philip Wadler and Stephen Blott for Standard ML but were first
   implemented in Haskell between 1987 and version 1.0.^[38]^[39]

   The first version of Haskell ("Haskell 1.0") was defined in 1990.^[1] The
   committee's efforts resulted in a series of language definitions (1.0,
   1.1, 1.2, 1.3, 1.4).

   [IMG]
   Enlarge
   Hierarchy of type classes in the Haskell prelude as of GHC 7.10. The
   inclusion of Foldable and Traversable (with corresponding changes to the
   type signatures of some functions), and of Applicative as intermediate
   between Functor and Monad, are deviations from the Haskell 2010 standard.

  Haskell 98[edit]

   In late 1997, the series culminated in Haskell 98, intended to specify a
   stable, minimal, portable version of the language and an accompanying
   standard library for teaching, and as a base for future extensions. The
   committee expressly welcomed creating extensions and variants of Haskell
   98 via adding and incorporating experimental features.^[37]

   In February 1999, the Haskell 98 language standard was originally
   published as The Haskell 98 Report.^[37] In January 2003, a revised
   version was published as Haskell 98 Language and Libraries: The Revised
   Report.^[29] The language continues to evolve rapidly, with the Glasgow
   Haskell Compiler (GHC) implementation representing the current de facto
   standard.^[40]

  Haskell 2010[edit]

   In early 2006, the process of defining a successor to the Haskell 98
   standard, informally named Haskell Prime, began.^[41] This was intended to
   be an ongoing incremental process to revise the language definition,
   producing a new revision up to once per year. The first revision, named
   Haskell 2010, was announced in November 2009^[2] and published in July
   2010.

   Haskell 2010 is an incremental update to the language, mostly
   incorporating several well-used and uncontroversial features previously
   enabled via compiler-specific flags.

     * Hierarchical module names. Module names are allowed to consist of
       dot-separated sequences of capitalized identifiers, rather than only
       one such identifier. This lets modules be named in a hierarchical
       manner (e.g., Data.List instead of List), although technically modules
       are still in a single monolithic namespace. This extension was
       specified in an addendum to Haskell 98 and was in practice universally
       used.
     * The foreign function interface (FFI) allows bindings to other
       programming languages. Only bindings to C are specified in the Report,
       but the design allows for other language bindings. To support this,
       data type declarations were permitted to contain no constructors,
       enabling robust nonce types for foreign data that could not be
       constructed in Haskell. This extension was also previously specified
       in an Addendum to the Haskell 98 Report and widely used.
     * So-called n+k patterns (definitions of the form fact (n+1) = (n+1) *
       fact n) were no longer allowed. This syntactic sugar had misleading
       semantics, in which the code looked like it used the (+) operator, but
       in fact desugared to code using (-) and (>=).
     * The rules of type inference were relaxed to allow more programs to
       type check.
     * Some syntax issues (changes in the formal grammar) were fixed: pattern
       guards were added, allowing pattern matching within guards; resolution
       of operator fixity was specified in a simpler way that reflected
       actual practice; an edge case in the interaction of the language's
       lexical syntax of operators and comments was addressed, and the
       interaction of do-notation and if-then-else was tweaked to eliminate
       unexpected syntax errors.
     * The LANGUAGE pragma was specified. By 2010, dozens of extensions to
       the language were in wide use, and GHC (among other compilers)
       provided the LANGUAGE pragma to specify individual extensions with a
       list of identifiers. Haskell 2010 compilers are required to support
       the Haskell2010 extension and are encouraged to support several
       others, which correspond to extensions added in Haskell 2010.

Features[edit]

   Main article: Haskell features
   Link: mw-deduplicated-inline-style
   See also: Glasgow Haskell Compiler § Extensions to Haskell

   Haskell features lazy evaluation, lambda expressions, pattern matching,
   list comprehension, type classes and type polymorphism. It is a purely
   functional language, which means that functions generally have no side
   effects. A distinct construct exists to represent side effects, orthogonal
   to the type of functions. A pure function can return a side effect that is
   subsequently executed, modeling the impure functions of other languages.

   Haskell has a strong, static type system based on Hindley–Milner type
   inference. Its principal innovation in this area is type classes,
   originally conceived as a principled way to add overloading to the
   language,^[42] but since finding many more uses.^[43]

   The construct that represents side-effects is an example of a monad: a
   general framework which can model various computations such as error
   handling, nondeterminism, parsing and software transactional memory. They
   are defined as ordinary datatypes, but Haskell provides some syntactic
   sugar for their use.

   Haskell has an open, published specification,^[29] and multiple
   implementations exist. Its main implementation, the Glasgow Haskell
   Compiler (GHC), is both an interpreter and native-code compiler that runs
   on most platforms. GHC is noted for its rich type system incorporating
   recent innovations such as generalized algebraic data types and type
   families. The Computer Language Benchmarks Game also highlights its
   high-performance implementation of concurrency and parallelism.^[44]

   An active, growing community exists around the language, and more than
   5,400 third-party open-source libraries and tools are available in the
   online package repository Hackage.^[45]

Code examples[edit]

   Link: mw-deduplicated-inline-style
   See also: Haskell features § Examples

   A "Hello, World!" program in Haskell (only the last line is strictly
   necessary):

 module Main (main) where          -- not needed in interpreter, is the default in a module file

 main :: IO ()                     -- the compiler can infer this type definition
 main = putStrLn "Hello, World!"

   The factorial function in Haskell, defined in a few different ways:

 -- [[Type signature|Type annotation]] (optional, same for each implementation)
 factorial :: (Integral a) => a -> a

 -- Using recursion (with the "ifthenelse" expression)
 factorial n = if n < 2
               then 1
               else n * factorial (n - 1)

 -- Using recursion (with pattern matching)
 factorial 0 = 1
 factorial n = n * factorial (n - 1)

 -- Using recursion (with guards)
 factorial n
    | n < 2     = 1
    | otherwise = n * factorial (n - 1)

 -- Using a list and the "product" function
 factorial n = product [1..n]

 -- Using fold (implements "product")
 factorial n = foldl (*) 1 [1..n]

 -- Point-free style
 factorial = foldr (*) 1 . enumFromTo 1

   As the Integer type has arbitrary-precision, this code will compute values
   such as factorial 100000 (a 456,574-digit number), with no loss of
   precision.

   An implementation of an algorithm similar to quick sort over lists, where
   the first element is taken as the pivot:

 -- Type annotation (optional, same for each implementation)
 quickSort :: Ord a => [a] -> [a]

 -- Using list comprehensions
 quickSort []     = []                               -- The empty list is already sorted
 quickSort (x:xs) = quickSort [a | a <- xs, a < x]   -- Sort the left part of the list
                    ++ [x] ++                        -- Insert pivot between two sorted parts
                    quickSort [a | a <- xs, a >= x]  -- Sort the right part of the list

 -- Using filter
 quickSort []     = []
 quickSort (x:xs) = quickSort (filter (<x) xs)
                    ++ [x] ++
                    quickSort (filter (>=x) xs)

Implementations[edit]

   All listed implementations are distributed under open source
   licenses.^[46]

   Implementations that fully or nearly comply with the Haskell 98 standard,
   include:

     * The Glasgow Haskell Compiler (GHC) compiles to native code on many
       different processor architectures, and to ANSI C, via one of two
       intermediate languages: C--, or in more recent versions, LLVM
       (formerly Low Level Virtual Machine) bitcode.^[47]^[48] GHC has become
       the de facto standard Haskell dialect.^[49] There are libraries (e.g.,
       bindings to OpenGL) that work only with GHC. GHC is also distributed
       with the Haskell platform.
     * Jhc, a Haskell compiler written by John Meacham, emphasizes speed and
       efficiency of generated programs and exploring new program
       transformations.
          * Ajhc is a fork of Jhc.
     * The Utrecht Haskell Compiler (UHC) is a Haskell implementation from
       Utrecht University.^[50] It supports almost all Haskell 98 features
       plus many experimental extensions. It is implemented using attribute
       grammars and is currently used mostly for research on generated type
       systems and language extensions.

   Implementations no longer actively maintained include:

     * The Haskell User's Gofer System (Hugs) is a bytecode interpreter. It
       was once one of the implementations used most widely, alongside the
       GHC compiler,^[51] but has now been mostly replaced by GHCi. It also
       comes with a graphics library.
     * HBC is an early implementation supporting Haskell 1.4. It was
       implemented by Lennart Augustsson in, and based on, Lazy ML. It has
       not been actively developed for some time.
     * nhc98 is a bytecode compiler focusing on minimizing memory use.
          * The York Haskell Compiler (Yhc) was a fork of nhc98, with the
            goals of being simpler, more portable and efficient, and
            integrating support for Hat, the Haskell tracer. It also had a
            JavaScript backend, allowing users to run Haskell programs in web
            browsers.

   Implementations not fully Haskell 98 compliant, and using a variant
   Haskell language, include:

     * Eta and Frege are dialects of Haskell targeting the Java Virtual
       Machine.
     * Gofer was an educational dialect of Haskell, with a feature called
       constructor classes, developed by Mark Jones. It was supplanted by
       Hugs (Haskell User's Gofer System).
     * Helium, a newer dialect of Haskell. The focus is on making learning
       easier via clearer error messages. It currently lacks full support for
       type classes, rendering it incompatible with many Haskell programs.

Notable applications[edit]

     * The proof assistant Agda is written in Haskell.^[52]
     * Cabal is a tool for building and packaging Haskell libraries and
       programs.^[53]
     * Darcs is a revision control system written in Haskell, with several
       innovative features, such as more precise control of patches to apply.
     * GHC is also often a testbed for advanced functional programming
       features and optimizations in other programming languages.
     * Git-annex is a tool to manage (big) data files under Git version
       control. It also provides a distributed file synchronization system
       (git-annex assistant).
     * Linspire Linux chose Haskell for system tools development.^[54]
     * Pandoc is a tool to convert one markup format into another.
     * Pugs is a compiler and interpreter for the Raku programming language
       (formerly Perl 6).
     * TidalCycles is a domain special language for live coding musical
       pattern, embedded in Haskell.^[55]
     * Xmonad is a window manager for the X Window System, written fully in
       Haskell.^[56]

  Industry[edit]

     * Bluespec SystemVerilog (BSV) is a language for semiconductor design
       that is an extension of Haskell. Also, Bluespec, Inc.'s tools are
       implemented in Haskell.
     * Cryptol, a language and toolchain for developing and verifying
       cryptography algorithms, is implemented in Haskell.
     * Facebook implements its anti-spam programs^[57] in Haskell,
       maintaining the underlying data access library as open-source
       software.^[58]
     * The Cardano blockchain platform is implemented in Haskell.^[59]
     * GitHub implemented Semantic, an open-source library for analysis,
       diffing, and interpretation of untrusted source code, in Haskell.^[60]
     * seL4, the first formally verified microkernel,^[61] used Haskell as a
       prototyping language for the OS developer.^[61]^: p.2  At the same
       time, the Haskell code defined an executable specification with which
       to reason, for automatic translation by the theorem-proving
       tool.^[61]^: p.3  The Haskell code thus served as an intermediate
       prototype before final C refinement.^[61]^: p.3 
     * Target stores' supply chain optimization software is written in
       Haskell. ^[62]

  Web[edit]

   Notable web frameworks written for Haskell include:^[63]

     * Snap
     * Yesod

Criticism[edit]

   Jan-Willem Maessen, in 2002, and Simon Peyton Jones, in 2003, discussed
   problems associated with lazy evaluation while also acknowledging the
   theoretical motives for it.^[64]^[65] In addition to purely practical
   considerations such as improved performance,^[66] they note that, in
   addition to adding some performance overhead, lazy evaluation makes it
   more difficult for programmers to reason about the performance of their
   code (particularly its space use).

   Bastiaan Heeren, Daan Leijen, and Arjan van IJzendoorn in 2003 also
   observed some stumbling blocks for Haskell learners: "The subtle syntax
   and sophisticated type system of Haskell are a double edged sword – highly
   appreciated by experienced programmers but also a source of frustration
   among beginners, since the generality of Haskell often leads to cryptic
   error messages."^[67] To address these, researchers from Utrecht
   University developed an advanced interpreter called Helium, which improved
   the user-friendliness of error messages by limiting the generality of some
   Haskell features, and in particular removing support for type classes.

   Ben Lippmeier designed Disciple^[68] as a strict-by-default (lazy by
   explicit annotation) dialect of Haskell with a type-and-effect system, to
   address Haskell's difficulties in reasoning about lazy evaluation and in
   using traditional data structures such as mutable arrays.^[69] He argues
   (p. 20) that "destructive update furnishes the programmer with two
   important and powerful tools ... a set of efficient array-like data
   structures for managing collections of objects, and ... the ability to
   broadcast a new value to all parts of a program with minimal burden on the
   programmer."

   Robert Harper, one of the authors of Standard ML, has given his reasons
   for not using Haskell to teach introductory programming. Among these are
   the difficulty of reasoning about resource use with non-strict evaluation,
   that lazy evaluation complicates the definition of datatypes and inductive
   reasoning,^[70] and the "inferiority" of Haskell's (old) class system
   compared to ML's module system.^[71]

   Haskell's build tool, Cabal, has historically been criticized for poorly
   handling multiple versions of the same library, a problem known as "Cabal
   hell". The Stackage server and Stack build tool were made in response to
   these criticisms.^[72] Cabal itself now has a much more sophisticated
   build system, heavily inspired by Nix,^[73] which became the default with
   version 3.0.

Related languages[edit]

   Clean is a close, slightly older relative of Haskell. Its biggest
   deviation from Haskell is in the use of uniqueness types instead of monads
   for I/O and side-effects.

   A series of languages inspired by Haskell, but with different type
   systems, have been developed, including:

     * Agda, a functional language with dependent types.
     * Cayenne, with dependent types.
     * Elm, a functional language to create web front-end apps, no support
       for user-defined or higher-kinded type classes or instances.
     * Epigram, a functional language with dependent types suitable for
       proving properties of programs.
     * Idris, a general purpose functional language with dependent types,
       developed at the University of St Andrews.
     * PureScript compiles to JavaScript.
     * Ωmega, strict and more.^[clarification needed]

   Other related languages include:

     * Curry, a functional/logic programming language based on Haskell.

   Notable Haskell variants include:

     * Generic Haskell, a version of Haskell with type system support for
       generic programming.
     * Hume, a strict functional language for embedded systems based on
       processes as stateless automata over a sort of tuples of one element
       mailbox channels where the state is kept by feedback into the
       mailboxes, and a mapping description from outputs to channels as box
       wiring, with a Haskell-like expression language and syntax.

Conferences and workshops[edit]

   The Haskell community meets regularly for research and development
   activities. The main events are:

     * International Conference on Functional Programming (ICFP)
     * Haskell Symposium (formerly the Haskell Workshop)
     * Haskell Implementors Workshop
     * Commercial Users of Functional Programming (CUFP)

   Starting in 2006, a series of organized hackathons has occurred, the Hac
   series, aimed at improving the programming language tools and
   libraries.^[74]

References[edit]

    1. ^ ^a ^b ^c Hudak et al. 2007.
    2. ^ ^a ^b Marlow, Simon (24 November 2009). "Announcing Haskell 2010".
       Haskell (Mailing list). Retrieved 12 March 2011.
    3. ^ ^a ^b
       Link: mw-deduplicated-inline-style
       Riedel, Herbert (28 April 2016). "ANN: Haskell Prime 2020 committee
       has formed". Haskell-prime (Mailing list). Retrieved 6 May 2017.
    4. ^ ^a ^b ^c ^d ^e ^f ^g ^h ^i ^j ^k ^l ^m Peyton Jones 2003, p. xi
    5. ^
       Link: mw-deduplicated-inline-style
       Norell, Ulf (2008). "Dependently Typed Programming in Agda" (PDF).
       Gothenburg: Chalmers University. Retrieved 9 February 2012.
    6. ^ Hudak et al. 2007, pp. 12–38, 43.
    7. ^
       Link: mw-deduplicated-inline-style
       Stroustrup, Bjarne; Sutton, Andrew (2011). "Design of Concept
       Libraries for C++" (PDF). Archived from the original (PDF) on 10
       February 2012. {{cite journal}}: Cite journal requires |journal=
       (help)
    8. ^ ^a ^b ^c ^d ^e ^f ^g ^h ^i ^j Hudak et al. 2007, pp. 12-45–46.
    9. ^ ^a ^b
       Link: mw-deduplicated-inline-style
       Meijer, Erik (2006). "Confessions of a Used Programming Language
       Salesman: Getting the Masses Hooked on Haskell". Oopsla 2007.
       CiteSeerX 10.1.1.72.868.
   10. ^
       Link: mw-deduplicated-inline-style
       Meijer, Erik (1 October 2009). "C9 Lectures: Dr. Erik Meijer –
       Functional Programming Fundamentals, Chapter 1 of 13". Channel 9.
       Microsoft. Retrieved 9 February 2012.
   11. ^
       Link: mw-deduplicated-inline-style
       Drobi, Sadek (4 March 2009). "Erik Meijer on LINQ". InfoQ. QCon SF
       2008: C4Media Inc. Retrieved 9 February 2012.{{cite news}}: CS1 maint:
       location (link)
   12. ^
       Link: mw-deduplicated-inline-style
       Hickey, Rich. "Clojure Bookshelf". Listmania!. Archived from the
       original on 3 October 2017. Retrieved 3 October 2017.
   13. ^
       Link: mw-deduplicated-inline-style
       Heller, Martin (18 October 2011). "Turn up your nose at Dart and smell
       the CoffeeScript". InfoWorld. Retrieved 2020-07-15.
   14. ^
       Link: mw-deduplicated-inline-style
       "Declarative programming in Escher" (PDF). Retrieved 7 October 2015.
   15. ^
       Link: mw-deduplicated-inline-style
       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. ^
       Link: mw-deduplicated-inline-style
       Wechsung, Ingo. "The Frege Programming Language" (PDF). Retrieved 26
       February 2014.
   17. ^
       Link: mw-deduplicated-inline-style
       "Facebook Introduces 'Hack,' the Programming Language of the Future".
       WIRED. 20 March 2014.
   18. ^
       Link: mw-deduplicated-inline-style
       "Idris, a dependently typed language". Retrieved 26 October 2014.
   19. ^
       Link: mw-deduplicated-inline-style
       "LiveScript Inspiration". Retrieved 4 February 2014.
   20. ^
       Link: mw-deduplicated-inline-style
       Freeman, Phil (2016). "PureScript by Example". Leanpub. Retrieved 23
       April 2017.
   21. ^
       Link: mw-deduplicated-inline-style
       Kuchling, A. M. "Functional Programming HOWTO". Python v2.7.2
       documentation. Python Software Foundation. Retrieved 9 February 2012.
   22. ^
       Link: mw-deduplicated-inline-style
       "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.
   23. ^
       Link: mw-deduplicated-inline-style
       "The Rust Reference: Appendix: Influences". Retrieved 3 February 2016.
   24. ^
       Link: mw-deduplicated-inline-style
       Fogus, Michael (6 August 2010). "MartinOdersky take(5) toList". Send
       More Paramedics. Retrieved 9 February 2012.
   25. ^
       Link: mw-deduplicated-inline-style
       Lattner, Chris (3 June 2014). "Chris Lattner's Homepage". Chris
       Lattner. Retrieved 3 June 2014. The Swift language is the product of
       tireless effort from a team of language experts, documentation gurus,
       compiler optimization ninjas, and an incredibly important internal
       dogfooding group who provided feedback to help refine and battle-test
       ideas. Of course, it also greatly benefited from the experiences
       hard-won by many other languages in the field, drawing ideas from
       Objective-C, Rust, Haskell, Ruby, Python, C#, CLU, and far too many
       others to list.
   26. ^
       Link: mw-deduplicated-inline-style
       "Timber/History". Retrieved 7 October 2015.
   27. ^
       Link: mw-deduplicated-inline-style
       Chevalier, Tim (28 January 2008). "anybody can tell me the
       pronunciation of "haskell"?". Haskell-cafe (Mailing list). Retrieved
       12 March 2011.
   28. ^ Type inference originally using Hindley-Milner type inference
   29. ^ ^a ^b ^c Peyton Jones 2003.
   30. ^ Edward Kmett, Edward Kmett – Type Classes vs. the World
   31. ^ GHC 2020 Team (29 October 2021) GHC 9.2.1 released
   32. ^
       Link: mw-deduplicated-inline-style
       Mossberg, Erik (8 June 2020), erkmos/haskell-companies, retrieved 22
       June 2020
   33. ^
       Link: mw-deduplicated-inline-style
       O'Sullivan, Bryan; Goerzen, John; Stewart, Donald Bruce (15 November
       2008). Real World Haskell: Code You Can Believe In. "O'Reilly Media,
       Inc.". pp. xxviii–xxxi. ISBN 978-0-596-55430-9.
   34. ^
       Link: mw-deduplicated-inline-style
       "Haskell in Production: Riskbook". Serokell Software Development
       Company. Retrieved 7 September 2021.
   35. ^
       Link: mw-deduplicated-inline-style
       "PYPL PopularitY of Programming Language index". pypl.github.io. May
       2021. Archived from the original on 7 May 2021. Retrieved 16 May 2021.
   36. ^
       Link: mw-deduplicated-inline-style
       Frederickson, Ben. "Ranking Programming Languages by GitHub Users".
       www.benfrederickson.com. Retrieved 6 September 2019.
   37. ^ ^a ^b ^c Peyton Jones 2003, Preface.
   38. ^ "Type classes, first proposed during the design of the Haskell
       programming language, ..." —John Garrett Morris (2013), "Type Classes
       and Instance Chains: A Relational Approach"
   39. ^
       Link: mw-deduplicated-inline-style
       Wadler, Philip (October 1988). "How to make ad-hoc polymorphism less
       ad hoc".
   40. ^
       Link: mw-deduplicated-inline-style
       "Haskell Wiki: Implementations". Retrieved 18 December 2012.
   41. ^
       Link: mw-deduplicated-inline-style
       "Welcome to Haskell'". The Haskell' Wiki. Archived from the original
       on 20 February 2016. Retrieved 11 February 2016.
   42. ^
       Link: mw-deduplicated-inline-style
       Wadler, P.; Blott, S. (1989). "How to make ad-hoc polymorphism less ad
       hoc". Proceedings of the 16th ACM SIGPLAN-SIGACT Symposium on
       Principles of Programming Languages. ACM: 60–76.
       doi:10.1145/75277.75283. ISBN 978-0-89791-294-5. S2CID 15327197.
   43. ^
       Link: mw-deduplicated-inline-style
       Hallgren, T. (January 2001). "Fun with Functional Dependencies, or
       Types as Values in Static Computations in Haskell". Proceedings of the
       Joint CS/CE Winter Meeting. Varberg, Sweden.
   44. ^ Computer Language Benchmarks Game
   45. ^
       Link: mw-deduplicated-inline-style
       "HackageDB statistics". Hackage.haskell.org. Archived from the
       original on 3 May 2013. Retrieved 26 June 2013.
   46. ^ "Implementations" at the Haskell Wiki
   47. ^
       Link: mw-deduplicated-inline-style
       "The LLVM Backend". GHC Trac.
   48. ^
       Link: mw-deduplicated-inline-style
       Terei, David A.; Chakravarty, Manuel M. T. (2010). "An LLVM Backend
       for GHC". Proceedings of ACM SIGPLAN Haskell Symposium 2010. ACM
       Press.
   49. ^ C. Ryder and S. Thompson (2005). "Porting HaRe to the GHC API"
   50. ^ Utrecht Haskell Compiler
   51. ^ Hudak et al. 2007, pp. 12–22.
   52. ^
       Link: mw-deduplicated-inline-style
       Agda 2, Agda Github Community, 15 October 2021, retrieved 16 October
       2021
   53. ^
       Link: mw-deduplicated-inline-style
       "The Haskell Cabal". Retrieved 8 April 2015.
   54. ^
       Link: mw-deduplicated-inline-style
       "Linspire/Freespire Core OS Team and Haskell". Debian Haskell mailing
       list. May 2006.
   55. ^
       Link: mw-deduplicated-inline-style
       "Live code with Tidal Cycles | Tidal Cycles". doc.tidalcycles.org.
       Retrieved 19 January 2022.
   56. ^ xmonad.org
   57. ^
       Link: mw-deduplicated-inline-style
       "Fighting spam with Haskell". Facebook Code. 26 June 2015. Retrieved
       11 August 2019.
   58. ^
       Link: mw-deduplicated-inline-style
       "Open-sourcing Haxl, a library for Haskell". Facebook Code. 10 June
       2014. Retrieved 11 August 2019.
   59. ^
       Link: mw-deduplicated-inline-style
       "input-output-hk/cardano-node: The core component that is used to
       participate in a Cardano decentralised blockchain". GitHub. Retrieved
       18 March 2022.
   60. ^
       Link: mw-deduplicated-inline-style
       Parsing, analyzing, and comparing source code across many languages:
       github/semantic, GitHub, 7 June 2019, retrieved 7 June 2019
   61. ^ ^a ^b ^c ^d A formal proof of functional correctness was completed
       in 2009.
       Link: mw-deduplicated-inline-style
       Klein, Gerwin; Elphinstone, Kevin; Heiser, Gernot; Andronick, June;
       Cock, David; Derrin, Philip; Elkaduwe, Dhammika; Engelhardt, Kai;
       Kolanski, Rafal; Norrish, Michael; Sewell, Thomas; Tuch, Harvey;
       Winwood, Simon (October 2009). "seL4: Formal verification of an OS
       kernel" (PDF). 22nd ACM Symposium on Operating System Principles. Big
       Sky, MT, USA.
   62. ^ Yula Gavrilova and Gints Dreimanis. Top 6 Software Projects Written
       in Haskell. Serokell Blog. October 17, 2019.
       <https://serokell.io/blog/top-software-written-in-haskell>. Accessed
       November 4, 2021
   63. ^
       Link: mw-deduplicated-inline-style
       "Web/Frameworks – HaskellWiki". wiki.haskell.org. Retrieved 11 August
       2019.
   64. ^ Jan-Willem Maessen. Eager Haskell: Resource-bounded execution yields
       efficient iteration. Proceedings of the 2002 Association for Computing
       Machinery (ACM) SIGPLAN workshop on Haskell.
   65. ^ Simon Peyton Jones. Wearing the hair shirt: a retrospective on
       Haskell. Invited talk at POPL 2003.
   66. ^
       Link: mw-deduplicated-inline-style
       "Lazy evaluation can lead to excellent performance, such as in The
       Computer Language Benchmarks Game".
   67. ^
       Link: mw-deduplicated-inline-style
       Heeren, Bastiaan; Leijen, Daan; van IJzendoorn, Arjan (2003). "Helium,
       for learning Haskell" (PDF). Proceedings of the 2003 ACM SIGPLAN
       Workshop on Haskell: 62–71. doi:10.1145/871895.871902.
       ISBN 1581137583. S2CID 11986908.
   68. ^
       Link: mw-deduplicated-inline-style
       "DDC – HaskellWiki". Haskell.org. 3 December 2010. Retrieved 26 June
       2013.
   69. ^ Ben Lippmeier, Type Inference and Optimisation for an Impure World,
       Australian National University (2010) PhD thesis, chapter 1
   70. ^
       Link: mw-deduplicated-inline-style
       Robert Harper. "The point of laziness". closed access
   71. ^
       Link: mw-deduplicated-inline-style
       Robert Harper. "Modules matter most". closed access
   72. ^
       Link: mw-deduplicated-inline-style
       "Solving Cabal Hell". www.yesodweb.com. Retrieved 11 August 2019.
   73. ^
       Link: mw-deduplicated-inline-style
       "Announcing cabal new-build: Nix-style local builds". Retrieved 1
       October 2019.
   74. ^
       Link: mw-deduplicated-inline-style
       "Hackathon – HaskellWiki".

Further reading[edit]

   Reports

     * Link: mw-deduplicated-inline-style
       Peyton Jones, Simon, ed. (2003). Haskell 98 Language and Libraries:
       The Revised Report. Cambridge University Press. ISBN 978-0521826143.
     * Link: mw-deduplicated-inline-style
       Marlow, Simon, ed. (2010). Haskell 2010 Language Report (PDF).
       Haskell.org.

   Textbooks

     * Link: mw-deduplicated-inline-style
       Davie, Antony (1992). An Introduction to Functional Programming
       Systems Using Haskell. Cambridge University Press.
       ISBN 978-0-521-25830-2.
     * Link: mw-deduplicated-inline-style
       Bird, Richard (1998). Introduction to Functional Programming using
       Haskell (2nd ed.). Prentice Hall Press. ISBN 978-0-13-484346-9.
     * Link: mw-deduplicated-inline-style
       Hudak, Paul (2000). The Haskell School of Expression: Learning
       Functional Programming through Multimedia. New York: Cambridge
       University Press. ISBN 978-0521643382.
     * Link: mw-deduplicated-inline-style
       Hutton, Graham (2007). Programming in Haskell. Cambridge University
       Press. ISBN 978-0521692694.
     * Link: mw-deduplicated-inline-style
       O'Sullivan, Bryan; Stewart, Don; Goerzen, John (2008). Real World
       Haskell. Sebastopol: O'Reilly. ISBN 978-0-596-51498-3 (full text)
       {{cite book}}: External link in |postscript= (help)CS1 maint:
       postscript (link)
     * Link: mw-deduplicated-inline-style
       Thompson, Simon (2011). Haskell: The Craft of Functional Programming
       (3rd ed.). Addison-Wesley. ISBN 978-0201882957.
     * Link: mw-deduplicated-inline-style
       Lipovača, Miran (April 2011). Learn You a Haskell for Great Good!. San
       Francisco: No Starch Press. ISBN 978-1-59327-283-8. (full text)
     * Link: mw-deduplicated-inline-style
       Bird, Richard (2014). Thinking Functionally with Haskell. Cambridge
       University Press. ISBN 978-1-107-45264-0.

   Tutorials

     * Link: mw-deduplicated-inline-style
       Hudak, Paul; Peterson, John; Fasel, Joseph (June 2000). "A Gentle
       Introduction To Haskell, Version 98". Haskell.org.
     * Yet Another Haskell Tutorial, by Hal Daumé III; assumes far less prior
       knowledge than official tutorial
     * Link: mw-deduplicated-inline-style
       Yorgey, Brent (12 March 2009). "The Typeclassopedia" (PDF). The
       Monad.Reader (13): 17–68.
     * Link: mw-deduplicated-inline-style
       Maguire, Sandy (2018). Thinking with Types: Type-Level Programming in
       Haskell.

   History

     * Link: mw-deduplicated-inline-style
       Hudak, Paul; Hughes, John; Peyton Jones, Simon; Wadler, Philip (2007).
       "A History of Haskell: Being Lazy with Class" (PDF). Proceedings of
       the Third ACM SIGPLAN Conference on History of Programming Languages
       (HOPL III): 12–1–55. doi:10.1145/1238844.1238856.
       ISBN 978-1-59593-766-7. S2CID 52847907.
     * Link: mw-deduplicated-inline-style
       Hamilton, Naomi (19 September 2008). "The A-Z of Programming
       Languages: Haskell". Computerworld.

External links[edit]

    Wikibooks has a book on the topic of: Haskell 

    Wikibooks has a book on the topic of: Write Yourself a Scheme in 48 Hours 

     * Official website Edit this at Wikidata
     * Official wiki

                                                             * Spain          
   Authority control: National libraries Edit this at        * France (data)  
   Wikidata                                                  * Germany        
                                                             * Israel         
                                                             * United States  

   Link: mw-deduplicated-inline-style

     * v        
     * t        
     * e        
   Programming languages
     * Comparison
     * Timeline 
     * History  
     * Ada      
     * ALGOL    
     * APL      
     * Assembly 
     * BASIC    
     * C        
     * C++      
     * C#       
     * COBOL    
     * Erlang   
     * Forth    
     * Fortran  
     * Go       
     * Haskell  
     * Java     
     * JavaScript
     * Kotlin   
     * Lisp     
     * Lua      
     * ML       
     * Pascal   
     * Perl     
     * PHP      
     * Prolog   
     * Python   
     * R        
     * Ruby     
     * Rust     
     * SQL      
     * Shell    
     * Simula   
     * Smalltalk
     * Swift    
     * more...  
     * Category 
     * Lists: Alphabetical
     * Categorical
     * Generational
     * Non-English-based

   Portal:
   [IMG]Computer programming
   Retrieved from
   "https://en.wikipedia.org/w/index.php?title=Haskell_(programming_language)&oldid=1077916796"
   Categories:
     * Academic programming languages
     * Educational programming languages
     * Functional languages
     * Haskell programming language family
     * Literate programming
     * Pattern matching programming languages
     * Programming languages created in 1990
     * Statically typed programming languages
   Hidden categories:
     * CS1 errors: missing periodical
     * CS1 maint: location
     * Articles with short description
     * Short description is different from Wikidata
     * Use dmy dates from November 2019
     * All articles with unsourced statements
     * Articles with unsourced statements from February 2012
     * Articles containing potentially dated statements from 2020
     * All articles containing potentially dated statements
     * Articles containing potentially dated statements from May 2021
     * Wikipedia articles needing clarification from June 2021
     * CS1 errors: external links
     * CS1 maint: postscript
     * Articles with BNE identifiers
     * Articles with BNF identifiers
     * Articles with GND identifiers
     * Articles with J9U identifiers
     * Articles with LCCN identifiers
     * Articles with example Haskell code

Navigation menu

   Personal tools
     * Not logged in
     * Talk
     * Contributions
     * Create account
     * Log in
   Namespaces
     * Article
     * Talk
   [ ] English
   Views
     * Read
     * Edit
     * View history
   [ ] More

  Search

   _____________________ [ Search ] [ Go ]
   Visit the main page
   Navigation
     * Main page
     * Contents
     * Current events
     * Random article
     * About Wikipedia
     * Contact us
     * Donate
   Contribute
     * Help
     * Learn to edit
     * Community portal
     * Recent changes
     * Upload file
   Tools
     * What links here
     * Related changes
     * Upload file
     * Special pages
     * Permanent link
     * Page information
     * Cite this page
     * Wikidata item
   Print/export
     * Download as PDF
     * Printable version
   In other projects
     * Wikimedia Commons
     * Wikibooks
     * Wikiquote
     * Wikiversity
   Languages
     * العربية
     * Azərbaycanca
     * বাংলা
     * Български
     * Català
     * Čeština
     * Dansk
     * Deutsch
     * Eesti
     * Ελληνικά
     * Español
     * Esperanto
     * Euskara
     * فارسی
     * Français
     * Galego
     * 한국어
     * हिन्दी
     * Hrvatski
     * Bahasa Indonesia
     * Íslenska
     * Italiano
     * עברית
     * Қазақша
     * Latina
     * Latviešu
     * Lëtzebuergesch
     * Magyar
     * മലയാളം
     * मराठी
     * Bahasa Melayu
     * Nederlands
     * 日本語
     * Norsk bokmål
     * ਪੰਜਾਬੀ
     * Polski
     * Português
     * Română
     * Русский
     * Simple English
     * Slovenčina
     * Slovenščina
     * Српски / srpski
     * Suomi
     * Svenska
     * ไทย
     * Тоҷикӣ
     * Türkçe
     * Українська
     * Tiếng Việt
     * 中文
   Edit links
     * This page was last edited on 18 March 2022, at 22:22 (UTC).
     * Text is available under the Creative Commons Attribution-ShareAlike
       License 3.0; additional terms may apply. By using this site, you agree
       to the Terms of Use and Privacy Policy. Wikipedia® is a registered
       trademark of the Wikimedia Foundation, Inc., a non-profit
       organization.
     * Privacy policy
     * About Wikipedia
     * Disclaimers
     * Contact Wikipedia
     * Mobile view
     * Developers
     * Statistics
     * Cookie statement
     * Wikimedia Foundation
     * Powered by MediaWiki
