Editing Functional programming (section)

== Applications ==

=== Text editors ===

[[Emacs]], a highly extensible text editor family uses its own [[Emacs Lisp|Lisp dialect]] for writing plugins. The original author of the most popular Emacs implementation, [[GNU Emacs]] and Emacs Lisp, [[Richard Stallman]] considers Lisp one of his favorite programming languages.<ref>{{Cite web |title=How I do my Computing |url=https://stallman.org/stallman-computing.html |access-date=2024-04-29 |website=stallman.org}}</ref>

[[Helix (text editor)|Helix]], since version 24.03 supports previewing [[Abstract syntax tree|AST]] as [[S-expression|S-expressions]], which are also the core feature of the Lisp programming language family.<ref>{{Cite web |title=Helix |url=https://helix-editor.com/news/release-24-03-highlights/ |access-date=2024-04-29 |website=helix-editor.com}}</ref>

=== Spreadsheets ===
[[Spreadsheet]]s can be considered a form of pure, [[Higher-order function|zeroth-order]], strict-evaluation functional programming system.<ref name="Wakeling2007">{{cite journal|last1=Wakeling|first1=David|title=Spreadsheet functional programming|journal=Journal of Functional Programming|volume=17|issue=1|year=2007|pages=131–143|issn=0956-7968|doi=10.1017/S0956796806006186|s2cid=29429059|url=http://www.activemode.org/webroot/Workers/ActiveTraining/Programming/Pro_SpreadsheetFunctionalProgramming.pdf}}</ref> However, spreadsheets generally lack higher-order functions as well as code reuse, and in some implementations, also lack recursion. Several extensions have been developed for spreadsheet programs to enable higher-order and reusable functions, but so far remain primarily academic in nature.<ref name="excel">{{cite web |title=Improving the world's most popular functional language: user-defined functions in Excel |first1=Simon |last1=Peyton Jones |author-link1=Simon Peyton Jones |first2=Margaret |last2=Burnett|author2-link=Margaret Burnett |first3=Alan |last3=Blackwell |author-link3=Alan Blackwell |url=http://research.microsoft.com/~simonpj/Papers/excel/index.htm |date=March 2003 |archive-url=https://web.archive.org/web/20051016011341/http://research.microsoft.com/~simonpj/Papers/excel/index.htm |archive-date=2005-10-16}}</ref>

=== Microservices ===
Due to their [[composability]], functional programming paradigms can be suitable for [[microservices]]-based architectures.<ref>{{Cite book |last=Rodger |first=Richard |title=The Tao of Microservices |date=11 December 2017 |publisher=Manning |isbn=9781638351733}}</ref>

=== Academia ===
Functional programming is an active area of research in the field of [[programming language theory]]. There are several [[peer-review]]ed publication venues focusing on functional programming, including the [[International Conference on Functional Programming]], the [[Journal of Functional Programming]], and the [[Symposium on Trends in Functional Programming]].

=== Industry ===
Functional programming has been employed in a wide range of industrial applications. For example, [[Erlang (programming language)|Erlang]], which was developed by the [[Sweden|Swedish]] company [[Ericsson]] in the late 1980s, was originally used to implement [[Fault tolerance|fault-tolerant]] [[telecommunications]] systems,<ref name="armstrong2007"/> but has since become popular for building a range of applications at companies such as [[Nortel]], [[Facebook]], [[Électricité de France]] and [[WhatsApp]].<ref name="erlang-faq"/><ref name="larson2009"/><ref>{{cite conference |last=Piro |first=Christopher |title=Functional Programming at Facebook |url=http://cufp.galois.com/2009/abstracts.html#ChristopherPiroEugeneLetuchy |year=2009 |conference=CUFP 2009 |access-date=2009-08-29 |archive-url=https://web.archive.org/web/20091017070140/http://cufp.galois.com/2009/abstracts.html#ChristopherPiroEugeneLetuchy |archive-date=2009-10-17 |url-status=dead }}</ref><ref name="Sim-Diasca"/><ref name="whatsapp.blog.2012">[http://blog.whatsapp.com/index.php/2012/01/1-million-is-so-2011/ 1 million is so 2011] {{Webarchive|url=https://web.archive.org/web/20140219234031/http://blog.whatsapp.com/index.php/2012/01/1-million-is-so-2011/ |date=2014-02-19}} // WhatsApp blog, 2012-01-06: "the last important piece of our infrastracture is Erlang"</ref> [[Scheme (programming language)|Scheme]], a dialect of [[Lisp (programming language)|Lisp]], was used as the basis for several applications on early [[Apple Macintosh]] computers<ref name="clinger1987"/><ref name="hartheimer1987"/> and has been applied to problems such as training-[[Computer simulation|simulation software]]<ref name="kidd2007"/> and [[telescope]] control.<ref name="cleis2006"/> [[OCaml]], which was introduced in the mid-1990s, has seen commercial use in areas such as financial analysis,<ref name="minksy2008"/> [[software driver|driver]] verification, industrial [[robot]] programming and static analysis of [[embedded software]].<ref name="leroy2007"/> [[Haskell]], though initially intended as a research language,<ref name="hudak2007"/> has also been applied in areas such as aerospace systems, hardware design and web programming.<ref name="haskell-industry"/><ref name="hudak2007"/>

Other functional programming languages that have seen use in industry include [[Scala (programming language)|Scala]],<ref>{{cite conference |last=Momtahan |first=Lee |title=Scala at EDF Trading: Implementing a Domain-Specific Language for Derivative Pricing with Scala |url=http://cufp.galois.com/2009/abstracts.html#LeeMomtahan |year=2009 |conference=CUFP 2009 |access-date=2009-08-29 |archive-url=https://web.archive.org/web/20091017070140/http://cufp.galois.com/2009/abstracts.html#LeeMomtahan |archive-date=2009-10-17 |url-status=dead }}</ref> [[F Sharp (programming language)|F#]],<ref name='quantFSharp'/><ref name='businessAppsFSharp'/> [[Wolfram Language]],<ref name="reference.wolfram.com"/> [[Lisp (programming language)|Lisp]],<ref>{{cite web |last=Graham |first=Paul |title=Beating the Averages |url=http://www.paulgraham.com/avg.html |year=2003 |access-date=2009-08-29}}</ref> [[Standard ML]]<ref>{{cite conference |last=Sims |first=Steve |title=Building a Startup with Standard ML |url=http://cufp.galois.com/2006/slides/SteveSims.pdf |year=2006 |conference=CUFP 2006 |access-date=2009-08-29}}</ref><ref>{{cite conference |last=Laurikari |first=Ville |title=Functional Programming in Communications Security. |url=http://cufp.galois.com/2007/abstracts.html#VilleLaurikari |year=2007 |conference=CUFP 2007 |access-date=2009-08-29 |archivedate=2010-12-21 |archiveurl=https://web.archive.org/web/20101221110947/http://cufp.galois.com/2007/abstracts.html#VilleLaurikari |url-status=dead }}</ref> and Clojure.<ref>{{cite web |url=http://www.infoq.com/news/2009/01/clojure_production |last=Lorimer |first=R. J. |title=Live Production Clojure Application Announced |date=19 January 2009|work=InfoQ}}</ref> Scala has been widely used in [[Data science]],<ref>{{Cite book |last=Bugnion |first=Pascal |title=Scala for Data Science |publisher=[[Packt]] |year=2016 |isbn=9781785281372 |edition=1st |language=en-US}}</ref> while [[ClojureScript]],<ref>{{Cite web |title=Why developers like ClojureScript |url=https://stackshare.io/clojurescript |access-date=2024-04-29 |website=StackShare |language=en}}</ref> [[Elm (programming language)|Elm]]<ref>{{Citation |last=Herrick |first=Justin |title=jah2488/elm-companies |date=2024-04-29 |url=https://github.com/jah2488/elm-companies |access-date=2024-04-29}}</ref> or [[PureScript]]<ref>{{Cite web |title=Why developers like PureScript |url=https://stackshare.io/purescript |access-date=2024-04-29 |website=StackShare |language=en}}</ref> are some of the functional frontend programming languages used in production. [[Elixir (programming language)|Elixir]]'s Phoenix framework is also used by some relatively popular commercial projects, such as [[Font Awesome]] or [[Allegro Platform|Allegro]] (one of the biggest e-commerce platforms in Poland)<ref>{{Cite web |last=Team |first=Editorial |date=2019-01-08 |title=ALLEGRO - all you need to know about the best Polish online marketplace |url=https://ecommercegermany.com/blog/allegro-all-you-need-to-know-about-the-best-polish-online-marketplace |access-date=2024-04-29 |website=E-commerce Germany News |language=en-US}}</ref>'s classified ads platform ''Allegro Lokalnie.''<ref>{{Cite web |title=Websites using Phoenix Framework - Wappalyzer |url=https://www.wappalyzer.com/technologies/web-frameworks/phoenix-framework/ |access-date=2024-04-29 |website=www.wappalyzer.com}}</ref>

Functional "platforms" have been popular in finance for risk analytics (particularly with large investment banks). Risk factors are coded as functions that form interdependent graphs (categories) to measure correlations in market shifts, similar in manner to [[Gröbner basis]] optimizations but also for regulatory frameworks such as [[Comprehensive Capital Analysis and Review]]. Given the use of OCaml and [[Caml]] variations in finance, these systems are sometimes considered related to a [[categorical abstract machine]]. Functional programming is heavily influenced by [[category theory]].{{Citation needed|date=August 2022}}

=== Education ===
Many [[University|universities]] teach functional programming.<ref name="oxfordFP">{{cite web|url=https://www.cs.ox.ac.uk/teaching/courses/2019-2020/fp/|title=Functional Programming: 2019-2020|publisher=University of Oxford Department of Computer Science|access-date=28 April 2020}}</ref><ref name="imperialFP">{{cite web|url=https://www.imperial.ac.uk/computing/current-students/courses/120_1/|title=Programming I (Haskell)|publisher=Imperial College London Department of Computing|access-date=28 April 2020}}</ref><ref name="nottinghamFP">{{cite web|url=https://www.nottingham.ac.uk/ugstudy/course/Computer-Science-BSc#yearsmodules|title=Computer Science BSc - Modules|access-date=28 April 2020}}</ref><ref name="mitFP">{{cite book|last1=Abelson|first1=Hal|author-link1=Hal Abelson|last2=Sussman|first2=Gerald Jay|author-link2=Gerald Jay Sussman |title=Structure and Interpretation of Computer Programs |url=http://mitpress.mit.edu/sicp/ |year=1985|publisher=MIT Press|chapter=Preface to the Second Edition|edition=2|bibcode=1985sicp.book.....A |chapter-url=https://mitpress.mit.edu/sites/default/files/sicp/full-text/book/book-Z-H-6.html}}</ref> Some treat it as an introductory programming concept<ref name="mitFP"/> while others first teach imperative programming methods.<ref name="nottinghamFP"/><ref name="61A">{{cite web|url=https://cs61a.org/articles/about.html|title=Computer Science 61A, Berkeley|author=John DeNero|date=Fall 2019|publisher=Department of Electrical Engineering and Computer Sciences, Berkeley|access-date=2020-08-14}}</ref>

Outside of computer science, functional programming is used to teach problem-solving, algebraic and geometric concepts.<ref name="bootstrapworld">{{Triangulation|196|Emmanuel Schanzer of Bootstrap}}</ref> It has also been used to teach classical mechanics, as in the book ''[[Structure and Interpretation of Classical Mechanics]]''.

In particular, [[Scheme (programming language)|Scheme]] has been a relatively popular choice for teaching programming for years.<ref>{{Cite web |title=Why Scheme for Introductory Programming? |url=https://home.adelphi.edu/sbloch/class/pbd/testimonials/ |access-date=2024-04-29 |website=home.adelphi.edu}}</ref><ref>{{Cite web |last=Staff |first=IMACS |date=2011-06-03 |title=What Is Scheme & Why Is it Beneficial for Students? |url=https://www.imacs.org/learn-computer-programming-using-scheme/ |access-date=2024-04-29 |website=IMACS – Making Better Thinkers for Life |language=en-US}}</ref>