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| name = F#
| logo = F Sharp logo.svg
| logo_sizelogo size = 128px
| logo caption = F# logomark
| paradigmparadigms = [[Programming paradigm#Multi-paradigm|Multi-paradigm]]: [[functional programming|functional]], [[imperative programming|imperative]], [[object-oriented programming|object-oriented]], [[agent-oriented programming|agent-oriented]], [[metaprogramming]], [[Reflection (computerReflective programming)|reflective]], [[concurrent programming|concurrent]]
| family = [[ML (programming language)|ML]]: [[Caml]]: [[OCaml]]
| released = {{Start date and age|2005}}, version 1.0
| designer = [[Don Syme]], [[Microsoft Research]]
| developer = [[Microsoft]], [[F Sharp Software Foundation|The F# Software Foundation]]
| released = {{Start date and age|2005}}, version 1.0
| latest_release_version = {{wikidata|property|reference|edit|Q648619|P348}} <!-- 7.0.3 here? since seen at (also 8.0 Preview 2 for F# as for .NET, also there?): https://github.com/dotnet/fsharp/releases -->
| latest_release_datelatest_release_version = {{start date and age|{{wikidata|qualifierproperty|reference|edit| Q648619 |P348|P577}}}}
| latest_release_date = {{start date and age|df=yes|{{wikidata|qualifier| Q648619 |P348|P577}}}}
| latest preview version =
| latest preview dateversion =
| latest preview date =
| typing = [[Static typing|Static]], [[Strong and weak typing|strong]], [[Type inference|inferred]]
| implementations =
| dialects =
| influenced by = [[C Sharp (programming language)|C#]], [[Erlang (programming language)|Erlang]], [[Haskell (programming language)|Haskell]],<ref name="haskellInfluence">{{harvcoltxt|Syme|Granicz|Cisternino|2007|p=2|quote=F# also draws from Haskell particularly with regard to two advanced language features called ''sequence expressions'' and ''workflows''.}}</ref> [[ML (programming language)|ML]], [[OCaml]],<ref name="historyMSR" /><ref name="ocamlOrigins">{{cite web |title=Leveraging .NET Meta-programming Components from F# |first1=Don |last1=Syme |authorlink1=Don Syme |url=http://research.microsoft.com/apps/pubs/default.aspx?id=147193|year=2006|quote=[F#] is rooted in the Core ML design, and in particular has a core language largely compatible with that of OCaml}}</ref> [[Python (programming language)|Python]], [[Scala (programming language)|Scala]]
| influenced = [[C Sharp (programming language)|C#]],<ref>for async</ref> [[Elm (programming language)|Elm]], [[F* (programming language)|F*]], [[LiveScript (programming language)|LiveScript]]
| programming language =
| operating system = [[Cross-platform software|Cross-platform]]: [[.NET Core|.NET]], [[.NET Framework]]framework, [[Mono (software)|Mono]]
| license = [[MIT License|MIT]]<ref>{{cite web |url=https://github.com/fsharp/fsharp/blob/master/License.txt |title=F# Software Foundation's License |website=[[GitHub]] |date=14 October 2021}}</ref><ref>{{cite web |url=https://github.com/Microsoft/visualfsharp/blob/master/License.txt |title=Microsoft's F# License |website=[[GitHub]] |date=16 October 2021}}</ref>
| website = {{URL|https://fsharp.org/}}
 
 
{{URL|https://learn.microsoft.com/en-us/dotnet/fsharp}}
| wikibooks = F Sharp Programming
| caption =
| file ext = .fs, .fsi, .fsx, .fsscript
}}
'''F#''' (pronounced '''F sharp''') is a functional-first, [[General-purpose programming language|general-purpose]], [[High-level programming language|high-level]], [[Strong and weak typing|strongly typed]], [[Programming paradigm#Multi-paradigm|multi-paradigm]] [[programming language]] that encompasses [[functional programming|functional]], [[imperative programming|imperative]], and [[object-oriented programming]] methods. It is most often used as a [[Cross-platform software|cross-platform]] [[Common Language Infrastructure]] (CLI) language on [[.NET Core|.NET]], but can also generate [[JavaScript]]<ref name="js">{{cite web |url= http://fsharp.org/use/web-apps/ |title= Using F# for Web Applications |author= The F# Software Foundation |access-date= 2020-07-30}}</ref> and [[graphics processing unit]] (GPU) code.<ref name="gpgpu">{{cite web |url= http://fsharp.org/use/gpu/ |archive-url= https://web.archive.org/web/20191225110926/http://fsharp.org/use/gpu/ |url-status= dead |archive-date= 2019-12-25 |title= Using F# for GPU Programming |author= The F# Software Foundation |access-date= 2019-12-25}}</ref>
 
F# is developed by the [[F Sharp Software Foundation|F# Software Foundation]],<ref name="fsharporg">{{cite web |url= http://fsharp.org |title= The F# Software Foundation |author= The F# Software Foundation |access-date= 2012-11-24}}</ref> [[Microsoft]] and open contributors. An [[Open-source software|open source]], cross-platform compiler for F# is available from the F# Software Foundation.<ref name="fsharposg">{{cite web |url= https://fsharp.github.io/ |title= F# Compiler (open source edition) @ github |author= The F# Software Foundation |access-date= 2012-11-24 |archive-date=2013-05-17 |archive-url=https://web.archive.org/web/20130517105109/http://fsharp.github.io/ |url-status=dead }}</ref> F# is a fully supported language in [[Microsoft Visual Studio|Visual Studio]]<ref>{{cite web |url= https://docs.microsoft.com/en-us/visualstudio/ide/fsharp-visual-studio |title= Develop with Visual F# in Visual Studio |access-date= 2020-07-30 }}</ref> and [[JetBrains#IDEs|JetBrains Rider]].<ref>{{cite web |url=https://www.jetbrains.com/help/rider/F_Sharp.html |title=F# |access-date= 2020-07-30 }}</ref> [[Plug-in (computing)|Plug-ins]] supporting F# exist for many widely used editors including [[Visual Studio Code]], [[Vim (text editor)|Vim]], and [[Emacs]].
 
F# is a member of the [[ML (programming language)|ML]] language family and originated as a [[.NET Framework]] implementation of a core of the programming language [[OCaml]].<ref name="historyMSR" /><ref name="ocamlOrigins" /> It has also been influenced by [[C Sharp (programming language)|C#]],
[[Python (programming language)|Python]], [[Haskell (programming language)|Haskell]],<ref name="haskellInfluence" /> [[Scala (programming language)|Scala]] and [[Erlang (programming language)|Erlang]].
 
==History==
 
===Versions===
 
{| class="wikitable"
|-
! F#<br/>version
! Version
! Language specification
! Date
Line 48 ⟶ 49:
! [[Runtime system|Runtime]]
|-
| F# 1.x
|
| May 2005<ref>{{cite web|last=Syme|first=Don|title=F# 1.0.8 released|url=http://blogs.msdn.com/b/dsyme/archive/2005/05/21/420795.aspx|publisher=Microsoft|access-date=September 7, 2014}}</ref>
Line 54 ⟶ 55:
|[[.NET Framework|.NET]] 1.0 - 3.5
|-
| F# 2.0
| [http://fsharp.org/specs/language-spec/index.html#f-20 August 2010]
| April 2010<ref>{{cite web|last=Syme|first=Don|title=F# 2.0 released as part of Visual Studio 2010|url=http://blogs.msdn.com/b/dsyme/archive/2010/04/12/f-2-0-released-as-part-of-visual-studio-2010.aspx|publisher=Microsoft|access-date=September 7, 2014}}</ref>
Line 60 ⟶ 61:
|[[.NET Framework|.NET]] 2.0 - 4.0, [[Mono (software)|Mono]]
|-
| F# 3.0
| [http://fsharp.org/specs/language-spec/index.html#f-30 November 2012]
| August 2012<ref>{{cite web|last=Zander|first=Jason|title=Visual Studio 2012 and .NET Framework 4.5 released to the web|url=http://blogs.msdn.com/b/jasonz/archive/2012/08/15/visual-studio-2012-and-net-framework-4-5-released-to-the-web.aspx|publisher=Microsoft|access-date=September 7, 2014}}</ref>
|[[Linux]], [[macOS]], [[Microsoft Windows|Windows]];<br />[[JavaScript]],<ref name="js"/> [[Graphics processing unit|GPU]]<ref name="gpgpu"/>
|[[.NET Framework|.NET]] 2.0 - 4.5, [[Mono (software)|Mono]]
|-
| F# 3.1
| [http://fsharp.org/specs/language-spec/index.html#f-31 November 2013]
| October 2013<ref>{{cite web|title=Visual Studio 2013 released to web|date=17 October 2013 |url=http://blogs.msdn.com/b/visualstudio/archive/2013/10/17/visual-studio-2013-released-to-web.aspx|publisher=Microsoft|access-date=September 7, 2014}}</ref>
|[[Linux]], [[macOS]], [[Microsoft Windows|Windows]];<br />[[JavaScript]],<ref name="js"/> [[Graphics processing unit|GPU]]<ref name="gpgpu"/>
|[[.NET Framework|.NET]] 2.0 - 4.5, [[Mono (software)|Mono]]
|-
| F# 4.0
| [http://fsharp.org/specs/language-spec/index.html#f-40 January 2016]
| July 2015<ref>{{cite web|title=Announcing the RTM of Visual F# 4.0|url=http://blogs.msdn.com/b/dotnet/archive/2015/07/20/announcing-the-rtm-of-visual-f-4-0.aspx|publisher=Microsoft|access-date=September 15, 2015}}</ref>
|<!-- [[Linux]], [[macOS]], [[Microsoft Windows|Windows]];<br />[[JavaScript]], [[Graphics processing unit|GPU]] -->
|<!-- [[.NET Framework|.NET]] 2.0 - 4.5, [[Mono (software)|Mono]] -->
|-
|F# 4.1
| [http://fsharp.org/specs/language-spec/index.html#f-41 May 2018]
|March 2017<ref>{{Cite news|url=https://blogs.msdn.microsoft.com/dotnet/2017/03/07/announcing-f-4-1-and-the-visual-f-tools-for-visual-studio-2017-2/|title=Announcing F# 4.1 and the Visual F# Tools for Visual Studio 2017|access-date=2017-03-08|language=en-US}}</ref>
|[[Linux]], [[macOS]], [[Microsoft Windows|Windows]],
[[JavaScript]],<ref name="js" /> [[Graphics processing unit|GPU]]<ref name="gpgpu" />
|[[.NET Framework|.NET]] 3.5 - 4.6.2, [[.NET Core]], [[Mono (software)|Mono]]
|-
|F# 4.5
|
|August 2018<ref>{{cite web|title=Announcing F# 4.5|date=14 August 2018|url=https://blogs.msdn.microsoft.com/dotnet/2018/08/14/announcing-f-4-5/|publisher=Microsoft|access-date=August 14, 2018}}</ref>
|[[Linux]], [[macOS]], [[Microsoft Windows|Windows]],
[[JavaScript]],<ref name="js" /> [[Graphics processing unit|GPU]]<ref name="gpgpu" />
| [[.NET Framework|.NET]] 4.5 - 4.7.2,<ref>{{Cite web|url=https://www.nuget.org/packages/FSharp.Core/4.5.0|title=FSharp.Core 4.5.0}}</ref> [[.NET Core]] Core SDK 2.1.400<ref>{{cite web|title=Download .NET Core 2.1 (Linux, macOS, and Windows)|url=https://dotnet.microsoft.com/download/dotnet/2.1|publisher=Microsoft|access-date=May 13, 2021}}</ref>
|-
|F# 4.6
|
|March 2019<ref>{{cite web|title=Announcing F# 4.6|date=29 March 2019|url=https://devblogs.microsoft.com/dotnet/announcing-f-4-6/|publisher=Microsoft|access-date=March 29, 2019}}</ref>
|[[Linux]], [[macOS]], [[Microsoft Windows|Windows]],
[[JavaScript]],<ref name="js" /> [[Graphics processing unit|GPU]]<ref name="gpgpu" />
| [[.NET Framework|.NET]] 4.5 - 4.7.2,<ref>{{Cite web|url=https://www.nuget.org/packages/FSharp.Core/4.6.0|title=FSharp.Core 4.6.0}}</ref> [[.NET Core]] Core SDK 2.2.300<ref>{{cite web|title=Download .NET Core 2.2 (Linux, macOS, and Windows)|url=https://dotnet.microsoft.com/download/dotnet/2.2|publisher=Microsoft|access-date=May 13, 2021}}</ref>
|-
|F# 4.7
|
|September 2019<ref>{{cite web|title=Announcing F# 4.7|date=23 September 2019|url=https://devblogs.microsoft.com/dotnet/announcing-f-4-7/|publisher=Microsoft|access-date=September 23, 2019}}</ref>
|[[Linux]], [[macOS]], [[Microsoft Windows|Windows]],
[[JavaScript]],<ref name="js" /> [[Graphics processing unit|GPU]]<ref name="gpgpu" />
| [[.NET Framework|.NET]] 4.5 - 4.8,<ref>{{Cite web|url=https://www.nuget.org/packages/FSharp.Core/4.7.0|title=FSharp.Core 4.7.0}}</ref> [[.NET Core]] Core SDK 3.0.100<ref>{{cite web|title=Download .NET Core 3.0 (Linux, macOS, and Windows)|url=https://dotnet.microsoft.com/download/dotnet/3.0|publisher=Microsoft|access-date=May 13, 2021}}</ref>
|-
|F# 5.0
|
|November 2020<ref name="blogs.msdn.microsoft.com2">{{Cite web|url=https://devblogs.microsoft.com/dotnet/announcing-f-5/|title = Announcing F# 5|date = November 10, 2020}}</ref>
|[[Linux]], [[macOS]], [[Microsoft Windows|Windows]],
[[JavaScript]],<ref name="js" /> [[Graphics processing unit|GPU]]<ref name="gpgpu" />
| [[.NET Core|.NET]] SDK 5.0.100<ref>{{cite web|title=Download .NET 5.0 (Linux, macOS, and Windows)|url=https://dotnet.microsoft.com/download/dotnet/5.0|publisher=Microsoft|access-date=May 13, 2021}}</ref>
|-
|F# 6.0
|
|November 2021<ref>{{Cite web|url=https://devblogs.microsoft.com/dotnet/fsharp-6-is-officially-here/|title = F# 6 is officially here!|date = November 9, 2021}}</ref>
|[[Linux]], [[macOS]], [[Microsoft Windows|Windows]],
[[JavaScript]],<ref name="js" /> [[Graphics processing unit|GPU]]<ref name="gpgpu" />
| [[.NET Core|.NET]] SDK 6.0.100<ref>{{cite web|title=Download .NET 6.0 (Linux, macOS, and Windows)|url=https://dotnet.microsoft.com/download/dotnet/6.0|publisher=Microsoft|access-date=November 14, 2021}}</ref>
 
|-
|F# 7.0
|
|November 2022<ref>{{Cite web|url=https://devblogs.microsoft.com/dotnet/announcing-fsharp-7/|title = Announcing F# 7|date = November 8, 2022}}</ref>
|[[Linux]], [[macOS]], [[Microsoft Windows|Windows]],
[[JavaScript]],<ref name="js" /> [[Graphics processing unit|GPU]]<ref name="gpgpu" />
| [[.NET Core|.NET]] SDK 7.0.100<ref>{{cite web|title=Download .NET 7.0 (Linux, macOS, and Windows)|url=https://dotnet.microsoft.com/en-us/download/dotnet/7.0|publisher=Microsoft|access-date=November 8, 2022}}</ref>
|-
 
| 8.0
|
|November 2023<ref>{{Cite web|url=https://devblogs.microsoft.com/dotnet/announcing-fsharp-8/|title=Announcing F# 8|date=November 14, 2023}}</ref>
|[[Linux]], [[macOS]], [[Microsoft Windows|Windows]],
[[JavaScript]],<ref name="js"/> [[Graphics processing unit|GPU]]<ref name="gpgpu"/>
| [[.NET]] SDK 8.0.100<ref>{{cite web|title=Download .NET 8.0 (Linux, macOS, and Windows)|url=https://dotnet.microsoft.com/en-us/download/dotnet/8.0|publisher=Microsoft|access-date=November 14, 2023}}</ref>
|-
| 9.0
|
|November 2024<ref>{{Cite web|url=https://learn.microsoft.com/en-us/dotnet/fsharp/whats-new/fsharp-9|title=What's new in F# 9|date=November 12, 2024}}</ref>
|[[Linux]], [[macOS]], [[Microsoft Windows|Windows]],
[[JavaScript]],<ref name="js"/> [[Graphics processing unit|GPU]]<ref name="gpgpu"/>
| [[.NET]] SDK 9.0.0<ref>{{cite web|title=Download .NET 9.0 (Linux, macOS, and Windows)|url=https://dotnet.microsoft.com/en-us/download/dotnet/9.0|publisher=Microsoft|access-date=January 13, 2025}}</ref>
|}
 
Line 135 ⟶ 148:
Earlier versions of the F# language were designed by [[Microsoft]] and [[Microsoft Research]] using a closed development process.
 
F# was first included in Visual Studio in the [[Visual_StudioVisual Studio#2010 | 2010 edition]], at the same level as [[Visual Basic (.NET) | Visual Basic]] and C# (albeit as an option), and has remainedremains in subsequentall later editions, thus making the language widely available and well-supported.
 
F# originates from Microsoft Research, Cambridge, UK. The language was originally designed and implemented by [[Don Syme]],<ref name="historyMSR">{{cite web |url= https://www.microsoft.com/en-us/research/project/f-at-microsoft-research/ |title= F# Historical Acknowledgements |website=[[Microsoft]]}}</ref> according to whom in the fsharp team, they say the F is for "Fun".<ref>{{cite web |url=http://www.networkworld.com/article/2271225/software/the-a-z-of-programming-languages--f-.html |title=The A-Z of programming languages: F# |last1=Edwards |first1=Kathryn |date=23 December 2008 |website=networkworld.com[[Network World]] |publisher=IDG |access-date=8 August 2016 |archive-date=13 November 2018 |archive-url=https://web.archive.org/web/20181113210720/https://www.networkworld.com/article/2271225/software/the-a-z-of-programming-languages--f-.html |url-status=dead }}</ref>
Andrew Kennedy contributed to the design of [[units of measure]].<ref name="historyMSR" /> The Visual F# Tools for Visual Studio are developed by Microsoft.<ref name="historyMSR" /> The F# Software Foundation developed the F# open-source compiler and tools, incorporating the open-source compiler implementation provided by the Microsoft Visual F# Tools team.<ref name="fsharporg" />
 
{| class="wikitable"
|+ Summary of versions
|-
! F#<br/>version
! !! Features added
! Features added
|-
!F# 1.0
|valign="top"|
* Functional programming
Line 160 ⟶ 174:
* Modules (no functors)
* Nested modules
* .NET Interoperabilityinteroperability
|-
!F# 2.0
|
* Active patterns
Line 177 ⟶ 191:
* Computation expressions
|-
!F# 3.0<ref>{{cite web|last=McNamara|first=Brian|title=More About F# 3.0 Language Features|url=http://blogs.msdn.com/b/fsharpteam/archive/2012/07/19/more-about-fsharp-3.0-language-features.aspx|access-date=September 7, 2014|publisher=Microsoft}}</ref>
|
* Type providers
Line 186 ⟶ 200:
* Provided units-of-measure
|-
!F# 3.1<ref>{{cite web|last=McNamara|first=Brian|title=Announcing a pre-release of F# 3.1|url=http://blogs.msdn.com/b/fsharpteam/archive/2013/06/27/announcing-a-pre-release-of-f-3-1-and-the-visual-f-tools-in-visual-studio-2013.aspx|access-date=September 7, 2014|publisher=Microsoft}}</ref>
|
* Named union type fields
Line 192 ⟶ 206:
* Type inference enhancements
|-
!F# 4.0<ref>{{Cite news|title=Announcing the RTM of Visual F# 4.0|language=en-US|url=https://blogs.msdn.microsoft.com/dotnet/2015/07/20/announcing-the-rtm-of-visual-f-4-0/|access-date=2017-03-08}}</ref>
|
* Printf on unitized values
Line 206 ⟶ 220:
* Params dictionaries
|-
!F# 4.1<ref>{{Cite news|title=Announcing F# 4.1 and the Visual F# Tools for Visual Studio 2017|language=en-US|url=https://blogs.msdn.microsoft.com/dotnet/2017/03/07/announcing-f-4-1-and-the-visual-f-tools-for-visual-studio-2017-2/|access-date=2017-03-08}}</ref>
|
* Struct tuples which inter-operate with C# tuples
Line 220 ⟶ 234:
* Support for 'fixed'
|-
!F# 4.5<ref name="blogs.msdn.microsoft.com2" />
|
* Versioning alignment of binary, package, and language
Line 235 ⟶ 249:
* Enumeration cases emitted as public
|-
!F# 4.6
|
* Anonymous record types
|-
!F# 4.7<ref name="blogs.msdn.microsoft.com.4.7">{{Cite web|url=https://devblogs.microsoft.com/dotnet/announcing-f-4-7/|title = Announcing F# 4.7|date = 23 September 2019}}</ref>
|
* Implicit yields
Line 247 ⟶ 261:
* Open static classes
|-
!F# 5.0<ref name="blogs.msdn.microsoft.com.5.0">{{Cite web|url=https://devblogs.microsoft.com/dotnet/announcing-f-5/|title = Announcing F# 5|date = 10 November 2020}}</ref>
|
* FSharp.Core now targets netstandard2.0 only
Line 264 ⟶ 278:
* Improved compiler analysis for library authors
|-
!F# 6.0<ref>{{Cite web|url=https://docs.microsoft.com/en-us/dotnet/fsharp/whats-new/fsharp-6|title = What's new in F# 6 - F# Guide|date=10 March 2023}}</ref>
|
* Tasks
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* “as” patterns
* Indentation syntax revisions
* AdditionalMore implicit conversions
* AdditionalMore implicit upcast conversions
* Implicit integer conversions
* First-class support for .NET-style implicit conversions
Line 281 ⟶ 295:
* InlineIfLambda optimizer directive
* Resumable code
* AdditionalMore collection functions
* Map has Keys and Values
* AdditionalMore intrinsics for NativePtr
* AdditionalMore numeric types with unit annotations
* Informational warnings for rarely used symbolic operators
|-
!F# 7.0<ref>{{Cite web |url=https://devblogs.microsoft.com/dotnet/announcing-fsharp-7/ |title = Announcing F# 7| |date=8 November 2022 }}</ref>
|
* Static abstract members support in interfaces
Line 302 ⟶ 316:
* Parallel type-checking and project-checking support (experimental, can be enabled via VS setting, or by tooling authors)
* Miscellaneous bugfixes and improvements.
|-
 
! 8.0<ref>{{Cite web|url=https://devblogs.microsoft.com/dotnet/announcing-fsharp-8/|title=Announcing F# 8| date=14 November 2023}}</ref>
|
* _.Property shorthand for (fun x -> x.Property)
* Nested record field copy and update
* while! (while bang) feature <ref>{{Cite web |url=https://devblogs.microsoft.com/dotnet/simplifying-fsharp-computations-with-the-new-while-keyword/ |title=Simplifying F# computations with the new 'while!' keyword' |date=20 September 2023}}</ref>
* Extended string interpolation syntax
* Use and compose string literals for printf and related functions
* Arithmetic operators in literals
* Type constraint intersection syntax
* Extended fixed binding
* Easier [<Extension>] method definition
* Static members in interfaces
* Static let in discriminated unions, records, structs, and types without primary constructors
* try-with within seq{}, [], and [||] collection expressions
* Recursive calls and yield! within exception handler
* Tail call attribute
* [<Struct>] unions can now have > 49 cases
* Strict indentation rules
* New diagnostics from the compiler
* Switches for compiler parallelization
|-
! 9.0<ref>{{Cite web|url=https://learn.microsoft.com/en-us/dotnet/fsharp/whats-new/fsharp-9|title=What's new in F# 9| date=12 November 2024}}</ref>
|
* Nullable reference types
* Discriminated union .Is* properties
* Partial active patterns can return bool instead of unit option
* Prefer extension methods to intrinsic properties when arguments are provided
* Empty-bodied computation expressions
* Hash directives are allowed to take non-string arguments
* Extended #help directive in fsi to show documentation in the REPL
* Allow #nowarn to support the FS prefix on error codes to disable warnings
* Warning about TailCall attribute on non-recursive functions or let-bound values
* Enforce attribute targets
* Updates to the standard library (FSharp.Core)
* Developer productivity improvements
* Performance improvements
* Improvements in tooling
|}
 
Line 308 ⟶ 359:
 
===Functional programming===
While supporting object-oriented features available in C#, F# is a [[Strong and weak typing|strongly typed]] functional-first language with a large number of capabilities that are normally found only in [[functional programming]] languages, while supporting object-oriented features available in C#. Together, these features allow F# programs to be written in a completely functional style and also allow functional and object-oriented styles to be mixed.
 
Examples of functional features are:
Line 326 ⟶ 377:
* [[List comprehension]]
* [[Monad (functional programming)|Monad]] pattern support (called ''computation expressions''<ref>{{Cite web|title=F Sharp Programming/Computation Expressions - Wikibooks, open books for an open world|url=https://en.wikibooks.org/wiki/F_Sharp_Programming/Computation_Expressions|access-date=2022-01-21|website=en.wikibooks.org|language=en}}</ref>)
* [[Tail call|Tail Callcall Optimisationoptimisation]]<ref>{{Cite web |last=kexugit |title=Tail calls in F# |url=https://docs.microsoft.com/en-us/archive/blogs/fsharpteam/tail-calls-in-f |access-date=2022-04-22 |website=docs.microsoft.com |date=8 July 2011 |language=en-us}}</ref>
 
F# is an expression-based language using [[eager evaluation]] and also in some instances [[lazy evaluation]]. Every statement in F#,
including <code>if</code> expressions, <code>try</code> expressions and loops, is a composable expression with a static type.<ref name="overview" /> Functions and expressions that do not return any value have a return type of <code>unit</code>. F# uses the <code>let</code> keyword for binding values to a name.<ref name="overview">{{cite web |url= http://tomasp.net/articles/fsharp-i-introduction/article.pdf |title= F# Language Overview |access-date= 2007-12-14}}</ref> For example:
<syntaxhighlight lang="fsharp">
let x = 3 + 4
Line 335 ⟶ 386:
binds the value <code>7</code> to the name <code>x</code>.
 
New types are defined using the <code>type</code> keyword. For functional programming, F# provides ''tuple'', ''record'', ''discriminated union'', ''list'', ''option'', and ''result'' types.<ref name="overview" /> A ''[[n-tuple|tuple]]'' represents a set of ''n'' values, where ''n'' ≥ 0. The value ''n'' is called the [[arity]] of the tuple. A 3-tuple would be represented as <code>(A, B, C)</code>, where A, B, and C are values of possibly different types. A tuple can be used to store values only when the number of values is known at design-time and stays constant during execution.
 
A ''record'' is a type where the data members are named. Here is an example of record definition:
Line 343 ⟶ 394:
Age : int }
</syntaxhighlight>
Records can be created as {{code|lang=fsharp|code=let r = { Name="AB"; Age=42 } }}. The <code>with</code> keyword is used to create a copy of a record, as in {{code|lang=fsharp|code={ r with Name="CD" } }}, which creates a new record by copying <code>r</code> and changing the value of the <code>Name</code> field (assuming the record created in the last example was named <code>r</code>).
 
A [[tagged union|discriminated union]] type is a [[type-safe]] version of [[union (computer science)|C unions]]. For example,
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The ''list'' type is an immutable [[linked list]] represented either using a {{code|lang=fsharp|code=head::tail}} notation (<code>::</code> is the [[cons]] operator) or a shorthand as {{code|lang=fsharp|code=[item1; item2; item3]}}. An empty list is written <code>[]</code>. The ''option'' type is a discriminated union type with choices <code>Some(x)</code> or <code>None</code>. F# types may be [[generic programming|generic]], implemented as generic .NET types.
 
F# supports [[lambda calculus|lambda functions]] and [[closure (computing)|closure]]s.<ref name="overview" /> All functions in F# are first class values and are immutable.<ref name="overview" /> Functions can be [[curry function|curried]]. Being first-class values, functions can be passed as arguments to other functions. Like other functional programming languages, F# allows [[function composition (computer science)|function composition]] using the <code>>></code> and <code><<</code> operators.
 
F# provides ''{{visible anchor|sequence expressions}}''<ref name="seq"/> that define a sequence <code>seq { ... }</code>, list <code>[ ... ]</code> or array <code>[| ... |]</code> through code that generates values. For example,
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forms a sequence of squares of numbers from 0 to 14 by filtering out numbers from the range of numbers from 0 to 25. Sequences are [[Generator (computer programming)|generators]] – values are generated on-demand (i.e., are [[lazy evaluation|lazily evaluated]]) – while lists and arrays are evaluated eagerly.
 
F# uses [[pattern matching]] to bind values to names. Pattern matching is also used when accessing discriminated unions – the union is value matched against pattern rules and a rule is selected when a match succeeds. F# also supports ''Activeactive Patternspatterns'' as a form of extensible pattern matching.<ref name="activePatterns" /> It is used, for example, when multiple ways of matching on a type exist.<ref name="overview" />
 
F# supports a general syntax for defining compositional computations called ''{{visible anchor|computation expressions}}''. Sequence expressions, asynchronous computations and queries are particular kinds of computation expressions. Computation expressions are an implementation of the [[monad (functional programming)|monad]] pattern.<ref name="seq">{{cite web |url= http://blogs.msdn.com/dsyme/archive/2007/09/22/some-details-on-f-computation-expressions-aka-monadic-or-workflow-syntax.aspx |title= Some Details on F# Computation Expressions |access-date= 2007-12-14}}</ref>
 
===Imperative programming===
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===Object-oriented programming===
Like other [[Common Language Infrastructure]] (CLI) languages, F# can use CLI types through object-oriented programming.<ref name="overview" /> F# support for object-oriented programming in expressions includes:
* Dot-notation, e.g., {{code|lang=fsharp|code=x.Name}}
* Object expressions, e.g., {{ code|lang=fsharp| code={ new obj() with member x.ToString() = "hello" } }}
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Support for object-oriented programming in patterns includes
* Type tests, e.g., {{code|lang=fsharp|code=:? string as s}}
* Active patterns, which can be defined over object types<ref name="activePatterns">{{cite web |url= http://www.developerfusion.com/article/133772/pattern-matching-in-f-part-2-active-patterns/ |title= Pattern Matching in F# Part 2 : Active Patterns |access-date= 2012-11-24 |archive-date= 2012-12-09 |archive-url= https://web.archive.org/web/20121209125518/http://www.developerfusion.com/article/133772/pattern-matching-in-f-part-2-active-patterns |url-status= dead }}</ref>
 
F# object type definitions can be class, struct, interface, enum, or delegate type definitions, corresponding to the definition forms found in [[C Sharp (programming language)|C#]]. For example, here is a class with a constructor taking a name and age, and declaring two properties.
Line 408 ⟶ 459:
 
===Asynchronous programming===
F# supports [[asynchronous programming]] through ''asynchronous workflows''.<ref name="aw" /> An asynchronous workflow is defined as a sequence of commands inside an <code>async{ ... }</code>, as in
<syntaxhighlight lang="fsharp">
let asynctask =
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return streamreader.ReadToEnd() }
</syntaxhighlight>
The <code>let!</code> indicates that the expression on the right (getting the response) should be done asynchronously but the flow should only continue when the result is available. In other words, from the point of view of the code block, it's as if getting the response is a blocking call, whereas from the point of view of the system, the thread won't be blocked and may be used to process other flows whileuntil the result needed for this one doesn't becomebecomes available.
 
The async block may be invoked using the <code>Async.RunSynchronously</code> function. Multiple async blocks can be executed in parallel using the <code>Async.Parallel</code> function that takes a list of <code>async</code> objects (in the example, <code>asynctask</code> is an async object) and creates another async object to run the tasks in the lists in parallel. The resultant object is invoked using <code>Async.RunSynchronously</code>.<ref name="aw">{{cite web |url= http://blogs.msdn.com/dsyme/archive/2007/10/11/introducing-f-asynchronous-workflows.aspx |title= Introducing F# Asynchronous Workflows |access-date= 2007-12-14}}</ref>
 
[[Inversion of control]] in F# follows this pattern.<ref name="aw" />
[[Inversion of control]] in F# follows this pattern.<ref name="aw"/>
 
Since version 6.0, F# supports creating, consuming and returning .NET tasks directly. <ref>{{cite web |url=https://learn.microsoft.com/en-us/dotnet/fsharp/language-reference/task-expressions | title=Task Expressions| date=19 April 2022|access-date=2023-01-15}}</ref>
 
<syntaxhighlight lang="fsharp">
open System.Net.Http
let fetchUrlAsync (url:string) = // string -> Task<string>
task {
use client = new HttpClient()
let! response = client.GetAsync(url)
let! content = response.Content.ReadAsStringAsync()
do! Task.Delay 500
return content
}
 
// Usage
let fetchPrint() =
let task = task {
let! data = fetchUrlAsync "https://example.com"
printfn $"{data}"
}
task.Wait()
 
</syntaxhighlight>
 
===Parallel programming===
Parallel programming is supported partly through the <code>Async.Parallel</code>, <code>Async.Start</code> and other operations that run asynchronous blocks in parallel.
 
Parallel programming is also supported through the <code>Array.Parallel</code> functional programming operators in the F# standard library, direct use of the <code>System.Threading.Tasks</code> task programming model, the direct use of .NET thread pool and .NET threads and through dynamic translation of F# code to alternative parallel execution engines such as [[Graphics processing unit|GPU]]<ref name="gpgpu" /> code.
 
===Units of measure===
The F# type system supports [[Units of measurement|units of measure]] checking for numbers.<ref name="units-msdn">{{cite web |url= http://msdn.microsoft.com/en-us/library/dd233243.aspx |title= Units of Measure (F#) |access-date= 2012-11-24}}</ref> The units of measure feature integrates with F# type inference to require minimal type annotations in user code.<ref name="units">{{cite web |url= http://blogs.msdn.com/b/andrewkennedy/archive/2008/08/29/units-of-measure-in-f-part-one-introducing-units.aspx |title= Units of Measure in F#: Part One, Introducing Units |access-date= 2012-11-24}}</ref>
 
In F#, you can assign units of measure, such as meters or kilograms, to floating point, unsigned integer<ref name="units extended">{{cite web|url=https://github.com/fsharp/fslang-design/blob/main/FSharp-6.0/FS-1091-Extend-Units-of-Measure.md| title=Extend Units of Measure to Include More Numeric Types | website=[[GitHub]] }}</ref> and signed integer values. This allows the compiler to check that arithmetic involving these values is dimensionally consistent, helping to prevent common programming mistakes by ensuring that, for instance, lengths aren't mistakenly added to times.
 
The units of measure feature integrates with F# type inference to require minimal type annotations in user code.<ref name="units">{{cite web |url=http://blogs.msdn.com/b/andrewkennedy/archive/2008/08/29/units-of-measure-in-f-part-one-introducing-units.aspx |title=Units of Measure in F#: Part One, Introducing Units |access-date=2012-11-24}}</ref>
 
 
<syntaxhighlight lang="fsharp">
[<Measure>] type m // meter
[<Measure>] type s // second
 
let distance = 100.0<m> // float<m>
let time = 5.0<s> // float<s>
let speed = distance/time // float<m/s>
 
 
[<Measure>] type kg // kilogram
[<Measure>] type N = (kg * m)/(s^2) // Newtons
[<Measure>] type Pa = N/(m^2) // Pascals
 
[<Measure>] type days
let better_age = 3u<days> // uint<days>
 
</syntaxhighlight>
 
The F# static type checker provides this functionality at compile time, but units are erased from the compiled code. Consequently, it is not possible to determine a value's unit at runtime.
 
===Metaprogramming===
F# allows some forms of syntax customizing via [[metaprogramming]] to support embedding custom [[___domain-specific language]]s within the F# language, particularly through computation expressions.<ref name="overview" />
 
F# includes a feature for run-time meta-programming called quotations.<ref name="quotations">{{cite web |url= http://msdn.microsoft.com/en-us/library/dd233212.aspx |title= Code Quotations (F#) |access-date= 2012-11-24}}</ref> A quotation expression evaluates to an abstract syntax tree representation of the F# expressions. Similarly, definitions labelled with the <code>[&lt;ReflectedDefinition&gt;]</code> attribute can also be accessed in their quotation form. F# quotations are used for various purposes including to compile F# code into [[JavaScript]]<ref name="js" /> and [[Graphics processing unit|GPU]]<ref name="gpgpu" /> code. (Quotations represent their F# code expressions as data for use by other parts of the program while requiring it to be syntactically correct F# code).
 
===Information-rich programming===
F# 3.0 introduced a form of compile-time meta-programming through statically extensible type generation called F# type providers.<ref name="typeproviders">{{cite web |url= http://msdn.microsoft.com/en-us/library/hh156509.aspx |title= Type Providers |access-date= 2012-11-24}}</ref> F# type providers allow the F# compiler and tools to be extended with components that provide type information to the compiler on-demand at compile time. F# type providers have been used to give strongly typed access to connected information sources in a scalable way, including to the [[Freebase (database)|Freebase]] knowledge graph.<ref>{{cite web |url= http://blogs.msdn.com/b/dsyme/archive/2012/09/21/new-tech-report-from-microsoft-research-strongly-typed-language-support-for-internet-scale-information-sources.aspx |title= New Tech Report from Microsoft Research: Strongly-Typed Language Support for Internet-Scale Information Sources |access-date= 2012-11-24}}</ref>
 
In F# 3.0 the F# quotation and computation expression features are combined to implement [[LINQ]] queries.<ref name="queries">{{cite web |url= http://msdn.microsoft.com/en-us/library/vstudio/hh225374.aspx |title= Query Expressions (F#) |access-date= 2012-11-24}}</ref> For example:
<syntaxhighlight lang="fsharp">
// Use the OData type provider to create types that can be used to access the Northwind database.
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</syntaxhighlight>
 
The combination of type providers, queries and strongly typed functional programming is known as ''information rich programming''.<ref name="irp">{{cite web |url= http://www.infoq.com/news/2011/09/Fsharp-3.0 |title= F# 3.0 – LINQ + Type Providers= Information Rich Programming |access-date= 2012-11-24}}</ref>
 
===Agent programming===
F# supports a variation of the [[Actor model|Actoractor]] programming model through the in-memory implementation of lightweight asynchronous agents. For example, the following code defines an agent and posts 2 messages:
 
<syntaxhighlight lang="fsharp">
type Message =
let counter =
| Enqueue of string
MailboxProcessor.Start(fun inbox ->
| Dequeue of AsyncReplyChannel<Option<string>>
let rec loop n =
 
async { do printfn "n = %d, waiting..." n
// Provides concurrent access to a list of strings
let! msg = inbox.Receive()
let listManager = MailboxProcessor.Start(fun inbox ->
return! loop(n+msg) }
looplet 0)rec messageLoop list = async {
let! msg = inbox.Receive()
match msg with
| Enqueue item ->
return! messageLoop (item :: list)
 
| Dequeue replyChannel ->
match list with
| [] ->
replyChannel.Reply None
return! messageLoop list
| head :: tail ->
replyChannel.Reply (Some head)
return! messageLoop tail
}
 
// Start the loop with an empty list
messageLoop []
)
 
// Usage
async {
// Enqueue some strings
listManager.Post(Enqueue "Hello")
listManager.Post(Enqueue "World")
 
// Dequeue and process the strings
let! str = listManager.PostAndAsyncReply(Dequeue)
str |> Option.iter (printfn "Dequeued: %s")
 
}
|> Async.Start
 
 
</syntaxhighlight>
 
==Development tools==
* [[Microsoft Visual Studio|Visual Studio]], with the Visual F# tools from [[Microsoft]] installed, can be used to create, run and debug F# projects. The Visual F# tools include a Visual Studio-hosted [[read–eval–print loop]] (REPL) interactive console that can execute F# code as it is written. Visual Studio for Mac also fully supports F# projects.
* [[Visual Studio Code]] contains full support for F# via the [http://ionide.io/ Ionide extension].
* F# can be developed with any text editor. Specific support exists in editors such as [[Emacs]].
* [[JetBrains]] Rider is optimized for the development of F# Code starting with release 2019.1.<ref>{{cite web|title=Rider 2019.1 Kicks off its Early Access Program!|author=Alexander Kurakin |date=15 March 2019 |url=https://blog.jetbrains.com/dotnet/2019/03/15/rider-2019-1-kicks-off-early-access-program/}}</ref>
* [[LINQPad]] has supported F# since version 2.x.{{whose|date=May 2022}}
===Comparison of integrated development environments===
{{excerpt|Comparison of integrated development environments|F#}}
 
==Application areas==
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The [https://safe-stack.github.io/ SAFE Stack] is an end-to-end F# stack to develop web applications. It uses [[ASP.NET Core]] on the server side and [https://fable.io Fable] on the client side.<ref>{{Cite web|url=http://fable.io/|title=Fable: JavaScript you can be proud of!|website=fable.io|access-date=2017-12-09}}</ref>
 
An alternativeAlternative end-to-end F# optionoptions isinclude the [[WebSharper]] framework and the Oxpecker framework.<ref name="websharper">{{cite web |url= http://websharper.com |title= WebSharper home |author= Intellifactory |access-date= 2012-11-24}}</ref>
 
===Cross-platform app development===
 
F# can be used together with the [https://visualstudio.microsoft.com/xamarin/ Visual Studio Tools for Xamarin] to develop apps for [[iOS]] and [[Android (operating system)|Android]]. The [https://fsprojects.github.iocom/fsprojects/Fabulous/ Fabulous] library provides a more comfortable functional interface.
 
=== Analytical programming ===
Among others, F# is used for quantitative finance programming,<ref>{{cite web |url= http://www.microsoft.com/casestudies/Case_Study_Detail.aspx?casestudyid=4000006794 |title= Microsoft Case Studies:Microsoft Visual Studio 2012 - Financial Services Firm |website= [[Microsoft]] |access-date= 2012-11-25}}</ref> energy trading and portfolio optimization,<ref>{{cite web |url= http://blogs.msdn.com/b/dsyme/archive/2011/01/12/f-for-energy-trading-and-energy-portfolio-optimization.aspx |title= F# for Energy Trading and Portfolio Optimization |access-date= 2012-11-25}}</ref> machine learning,<ref>{{cite web |url= http://www.microsoft.com/casestudies/Case_Study_Detail.aspx?CaseStudyID=4000005226 |title= Microsoft Case Study: Grange Insurance |website= [[Microsoft]] |access-date= 2012-11-25}}</ref> business intelligence<ref>{{cite book |chapter-url= http://dl.acm.org/citation.cfm?id=1362702.1362709&coll=ACM&dl=ACM&type=series&idx=SERIES824%25E2%2588%2582=series&WantType=Proceedings&title=ICFP |chapter= Learning with F# |doi= 10.1145/1362702.1362709 |access-date= 2012-11-25|title= Proceedings of the 4th ACM SIGPLAN workshop on Commercial users of functional programming - CUFP '07 |year= 2007 |last1= Trelford |first1= Phil |series= Cufp '07 |pages= 1–2 |isbn= 9781450378444 |s2cid= 24018363 }}</ref> and social gaming on [[Facebook]].<ref>{{cite web |url= http://blogs.msdn.com/b/dsyme/archive/2012/10/23/f-job-in-social-gaming-inn-london.aspx |title= F# Job in Facebook Social Gaming |access-date= 2012-11-25}}</ref>
 
In the 2010s, F# has been positioned as an optimized alternative to [[C Sharp (programming language)|C#]]. F#'s scripting ability and inter-language compatibility with all Microsoft products have made it popular among developers.<ref>{{cite web |url= https://fsharp.org/testimonials/ |title= F# Developer Testimonials |access-date= May 25, 2021}}</ref>
 
===Scripting===
F# can be used as a scripting language, mainly for desktop [[read–eval–print loop]] (REPL) scripting.<ref>{{cite web |url= https://docs.microsoft.com/en-gb/archive/blogs/chrsmith/scripting-in-f |title= Scripting in F# |date=12 September 2008 |access-date= 2020-01-17}}</ref>
 
==Open-source community==
The F# [[Open-source model|open-source]] community includes the F# Software Foundation<ref name="fsharporg" /> and the F# Open Source Group at [[GitHub]].<ref name="fsharposg" /> Popular open-source F# projects include:
 
* [https://fable.io/ Fable], an F# to Javascript transpiler based on [https://babeljs.io Babel].
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printfn "Hello World!"
</syntaxhighlight>
A record type definition. Records are immutable by default and are compared by structural equality.
 
<syntaxhighlight lang="fsharp">
type Person = {
FirstName: string
LastName: string
Age: int
}
 
// Creating an instance of the record
let person = { FirstName = "John"; LastName = "Doe"; Age = 30 }
</syntaxhighlight>
 
 
A Person class with a constructor taking a name and age and two immutable properties.
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let printList lst =
for x in lst do
printfn $"%d{x}" x
 
/// Iteration using a higher-order function
Line 563 ⟶ 712:
<syntaxhighlight lang="fsharp">
/// Fibonacci Number formula
[<TailCall>]
let fib n =
let rec g n f0 f1 =
Line 638 ⟶ 788:
 
==Notes==
{{Reflist|30em}}
 
==References==
Line 647 ⟶ 797:
* {{citation |first=Tomas |last=Petricek |title=Real World Functional Programming With Examples in F# and C# |year=2009 |publisher=[[Manning Publications]]}}
* {{citation |first1=Michael |last1=Hansen|first2=Hans |last2=Rischel |title=Functional Programming Using F# |year=2013 |publisher=[[Cambridge University Press]]}}
* {{citation |first1=Johan|last1=Astborg |title= F# for Quantitative Finance |url= https://www.packtpub.com/big-data-and-business-intelligence/f-quantitative-finance |year=2013 |publisher=[[Packt Publishing]]}}
* {{citation |first1=Mikael|last1=Lundin |title= Testing with F# |url= https://www.packtpub.com/application-development/testing-f |year=2015 |publisher=[[Packt Publishing]]}}
 
==External links==
{{Wikibooks|F Sharp Programming}}
* {{Official website|https://fsharp.org/}} The F# Software Foundation
* [https://fsharp.github.io The F# Open Source Group at GitHub] {{Webarchive|url=https://web.archive.org/web/20130517105109/http://fsharp.github.io/ |date=2013-05-17 }}
* [https://fsharp.net/ The Visual F# Developer Center] {{Webarchive|url=https://web.archive.org/web/20081119161341/http://www.fsharp.net/ |date=2008-11-19 }}
* [https://web.archive.org/web/20140703090417/http://tsunami.io/ Tsunami, an embeddable desktop F# IDE]
* [https://web.archive.org/web/20130921130415/http://tsunami.io/cloud_tsunami.html Cloud Tsunami, an embeddable Silverlight F# IDE]
* [https://web.archive.org/web/20121130163443/http://www.tryfsharp.org/ Try F#, for learning F# in a web browser]
* [http://fssnip.net F# Snippets Site]
* [https://learn.microsoft.com/en-us/archive/blogs/fsharpteam/ The Visual F# team blog]
* [https://www.microsoft.com/en-us/research/project/f-at-microsoft-research/ The original Microsoft Research website for F#]
* [http://feedproxy.google.com/planet_fsharp Planet F#] {{Webarchive|url=https://web.archive.org/web/20090213202656/http://feedproxy.google.com/planet_fsharp |date=2009-02-13 }}
* [https://web.archive.org/web/20110715231625/http://www.ctocorner.com/fsharp/book/default.aspx The F# Survival Guide, Dec 2009 (Web-based book)]
* [http://fsharp.org/specs/language-spec/ The F# Language Specification]
* [http://www.developerfusion.com/article/122079/intro-to-f/ An introduction to F# programming] {{Webarchive|url=https://web.archive.org/web/20110713133206/http://www.developerfusion.com/article/122079/intro-to-f/ |date=2011-07-13 }}
* [http://opcoast.com/demos/fsharp/index.html A tutorial showing the ''process'' of reaching a functional design; includes test and parallel coding]
 
{{ML programming}}
{{.NET Framework}}
{{Common Language Infrastructure}}
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[[Category:.NET programming languages]]
[[Category:Cross-platform free software]]
[[Category:High-level programming languages]]
[[Category:Functional languages]]
[[Category:Microsoft free software]]
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[[Category:Software using the MIT license]]
[[Category:Statically typed programming languages]]
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