Functional programming: Difference between revisions

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Church later developed a weaker system, the [[simply typed lambda calculus]], which extended the lambda calculus by assigning a [[data type]] to all terms.<ref>{{cite journal |last1=Church |author-link=Alonzo Church |first1=A. |year=1940 |title=A Formulation of the Simple Theory of Types |journal=Journal of Symbolic Logic |volume=5 |issue=2 |pages=56–68 |doi=10.2307/2266170 |jstor=2266170| s2cid=15889861}}</ref> This forms the basis for statically typed functional programming.

The first [[High-level programming language|high-level]] functional programming language, [[Lisp (programming language)|Lisp]], was developed in the late 1950s for the [[IBM 700/7000 series#Scientific Architecture|IBM 700/7000 series]] of scientific computers by [[John McCarthy (computer scientist)|John McCarthy]] while at [[Massachusetts Institute of Technology]] (MIT).<ref>{{cite conferencebook |first=John |last=McCarthy |author-link=John McCarthy (computer scientist) |title=The first ACM SIGPLAN conference on History of Lispprogramming languages - HOPL-1 |journalchapter=History of Programming LanguagesLISP |pages=173–185 |date=June 1978 |url=http://jmc.stanford.edu/articles/lisp/lisp.pdf|doi=10.1145/800025.808387 |place=Los Angeles, CA}}</ref> Lisp functions were defined using Church's lambda notation, extended with a label construct to allow [[Recursion (computer science)|recursive]] functions.<ref>{{cite journal|author=John McCarthy|author-link=John McCarthy (computer scientist)|title=Recursive functions of symbolic expressions and their computation by machine, Part I.|journal=Communications of the ACM|volume=3|issue=4|year=1960|pages=184–195|url=http://jmc.stanford.edu/articles/recursive/recursive.pdf|publisher=ACM New York, NY, US|doi=10.1145/367177.367199|s2cid=1489409}}</ref> Lisp first introduced many paradigmatic features of functional programming, though early Lisps were [[Programming paradigm#Multi-paradigm|multi-paradigm languages]], and incorporated support for numerous programming styles as new paradigms evolved. Later dialects, such as [[Scheme (programming language)|Scheme]] and [[Clojure]], and offshoots such as [[Dylan (programming language)|Dylan]] and [[Julia (programming language)|Julia]], sought to simplify and rationalise Lisp around a cleanly functional core, while [[Common Lisp]] was designed to preserve and update the paradigmatic features of the numerous older dialects it replaced.<ref>{{cite book|author1=Guy L. Steele |author2=Richard P. Gabriel |title=History of programming languages---II |chapter=The evolution of Lisp |pages= 233–330 |date=February 1996 |url=http://dreamsongs.com/Files/HOPL2-Uncut.pdf |doi= 10.1145/234286.1057818 |isbn=978-0-201-89502-5 |s2cid=47047140}}</ref>

[[Information Processing Language]] (IPL), 1956, is sometimes cited as the first computer-based functional programming language.<ref>The memoir of [[Herbert A. Simon]] (1991), ''Models of My Life'' pp.189-190 {{ISBN|0-465-04640-1}} claims that he, Al Newell, and Cliff Shaw are "...commonly adjudged to be the parents of [the] artificial intelligence [field]," for writing [[Logic Theorist]], a program that proved theorems from ''[[Principia Mathematica]]'' automatically. To accomplish this, they had to invent a language and a paradigm that, viewed retrospectively, embeds functional programming.</ref> It is an [[assembly language|assembly-style language]] for manipulating lists of symbols. It does have a notion of ''generator'', which amounts to a function that accepts a function as an argument, and, since it is a [[Low-level programming language|low-level programming language]], code can be data, so IPL can be regarded as having higher-order functions. However, it relies heavily on the mutating list structure and similar imperative features.

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In [[C Sharp (programming language)|C#]], anonymous classes are not necessary, because closures and lambdas are fully supported. Libraries and language extensions for immutable data structures are being developed to aid programming in the functional style in C#.

Many [[Object-oriented programming|object-oriented]] [[Design pattern (computer science)|design patterns]] are expressible in functional programming terms: for example, the [[strategy pattern]] simply dictates use of a higher-order function, and the [[visitor (design pattern)|visitor]] pattern roughly corresponds to a [[catamorphism]], or [[fold (higher-order function)|fold]].

Similarly, the idea of immutable data from functional programming is often included in imperative programming languages,<ref>{{cite book |title=Effective Java |edition=Second |first=Joshua |last=Bloch |chapter=Item 15: Minimize Mutability |isbn=978-0321356680 |date=2008 |publisher=Addison-Wesley |url-access=registration |url=https://archive.org/details/effectivejava00bloc_0}}</ref> for example the tuple in Python, which is an immutable array, and Object.freeze() in JavaScript.<ref>{{Cite web|last=|first=|date=|title=Object.freeze() - JavaScript {{!}} MDN|url=https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/freeze|access-date=2021-01-04|website=developer.mozilla.org|quote=The Object.freeze() method freezes an object. A frozen object can no longer be changed; freezing an object prevents new properties from being added to it, existing properties from being removed, prevents changing the enumerability, configurability, or writability of existing properties, and prevents the values of existing properties from being changed. In addition, freezing an object also prevents its prototype from being changed. freeze() returns the same object that was passed in.}}</ref>

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<ref name="larson2009">{{cite journal |last=Larson |first=Jim |title=Erlang for concurrent programming |journal=Communications of the ACM |volume= 52 |issue= 3 |date=March 2009 |doi=10.1145/1467247.1467263 |page=48 |s2cid=524392 |doi-access=free}}</ref>

<ref name="minksy2008">{{cite journal |last1=Minsky |first1=Yaron |last2=Weeks |first2=Stephen |title=Caml Trading&nbsp;— experiences with functional programming on Wall Street |journal=Journal of Functional Programming |volume=18 |issue=4 |pages=553–564 |date=July 2008 |doi=10.1017/S095679680800676X |doi-broken-date=4 June 2025 |s2cid=30955392 |doi-access=free }}</ref>

<ref name="leroy2007">{{cite conference |last=Leroy |first=Xavier |title=Some uses of Caml in Industry |url=http://cufp.galois.com/2007/slides/XavierLeroy.pdf |conference=CUFP 2007 |access-date=2009-08-26 |archivedate=2011-10-08 |archiveurl=https://web.archive.org/web/20111008170929/http://cufp.galois.com/2007/slides/XavierLeroy.pdf |url-status=dead }}</ref><ref name="haskell-industry">{{cite web |title=Haskell in industry |work=Haskell Wiki |url=http://www.haskell.org/haskellwiki/Haskell_in_industry |access-date=2009-08-26 |quote=Haskell has a diverse range of use commercially, from aerospace and defense, to finance, to web startups, hardware design firms and lawnmower manufacturers.}}</ref>

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<ref name="Amath-CO">{{cite web |website=Department of Applied Math |publisher=University of Colorado |title=Functional vs. Procedural Programming Language |url=http://amath.colorado.edu/computing/mmm/funcproc.html |archive-url=https://web.archive.org/web/20071113175801/http://amath.colorado.edu/computing/mmm/funcproc.html |archive-date=2007-11-13 |access-date=2006-08-28 |url-status=dead }}</ref>

<ref name="Novatchev">{{cite web |url=httphttps://fxsl.sourceforge.net/articles/FuncProg/Functional%20Programming.html |first=Dimitre |last=Novatchev |title=The Functional Programming Language XSLT — A proof through examples |access-date=May 27, 2006}}</ref><ref name="Mertz">{{cite web |url=http://gnosis.cx/publish/programming/xml_models_fp.html |first=David |last=Mertz |title=XML Programming Paradigms (part four): Functional Programming approached to XML processing |access-date=May 27, 2006 |work=IBM developerWorks}}</ref>

<ref name="Chamberlin_Boyce">{{cite journal |title=SEQUEL: A structured English query language |first1=Donald D. |last1=Chamberlin |author-link1=Donald D. Chamberlin |first2=Raymond F. |last2=Boyce |author-link2=Raymond F. Boyce |journal=Proceedings of the 1974 ACM SIGFIDET |pages=249–264 |year=1974}}</ref><ref name="Sim-Diasca">{{cite web |title=Sim-Diasca: a large-scale discrete event concurrent simulation engine in Erlang |url=http://research.edf.com/research-and-the-scientific-community/software/sim-diasca-80704.html |date=November 2011 |access-date=2011-11-08 |archive-date=2013-09-17 |archive-url=https://web.archive.org/web/20130917092159/http://research.edf.com/research-and-the-scientific-community/software/sim-diasca-80704.html |url-status=dead }}</ref>