F# - Programming language

F# is an open source programming language created in 2005 by Don Syme.

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19Years Old

F# (pronounced F sharp) is a strongly typed, multi-paradigm programming language that encompasses functional, imperative, and object-oriented programming methods. F# is most often used as a cross-platform Common Language Infrastructure (CLI) language, but it can also generate JavaScript and graphics processing unit (GPU) code. F# is developed by the F# Software Foundation, Microsoft and open contributors. Read more on Wikipedia...

F# website
F# Wikipedia page
F# docs
F# first developed in Microsoft Research
The Google BigQuery Public Dataset GitHub snapshot shows 4k users using F# in 6k repos on GitHub
Check out the 128 F# meetup groups on Meetup.com.
There are 1,245 Project Euler users using F#
In the 2021 StackOverflow developer survey F# programmers reported a median salary of $81,037. 1% of respondents reported using F#. 804 programmers reported using F#, and 2,157 said they wanted to use it
F# on HOPL
F# appears in the TIOBE Index
F# Ubuntu package
Monaco package for syntax highlighting F#
Pygments supports syntax highlighting for F#
GitHub supports syntax highlighting for F#
F# appears in the Quine Relay project
There is 1 Jupyter Kernel for F#
There is a central package repository for F#
Release Notes for F#
Frequently Asked Questions for F#
Read more about F# on the web: 1.

Example from Compiler Explorer:

module Program

let square num = num * num

Example from Riju:

printfn "Hello, world!"

Example from hello-world:

printfn "Hello World"

Example from the Hello World Collection:

(* Hello World in F# *)

printf "Hello World!\n"

Example from Linguist:

module Sample

open System

type Foo =
    {
        Bar : string
    }

type Baz = interface end

let Sample1(xs : int list) : string =
    xs
    |> List.map (fun x -> string x)
    |> String.concat ","

Example from Wikipedia:

/// A simple prime number detector
let isPrime (n:int) =
   let bound = int (sqrt (float n))
   seq {2 .. bound} |> Seq.forall (fun x -> n % x <> 0)

// We are using async workflows
let primeAsync n =
    async { return (n, isPrime n) }

/// Return primes between m and n using multiple threads
let primes m n =
    seq {m .. n}
        |> Seq.map primeAsync
        |> Async.Parallel
        |> Async.RunSynchronously
        |> Array.filter snd
        |> Array.map fst

// Run a test
primes 1000000 1002000
    |> Array.iter (printfn "%d")

F# Keywords

abstract and atomic as assert asr base begin break checked component const constraint constructor continue class default delegate do done downcast downto elif else end exception eager event external extern false finally for fun function fixed functor global if in include inherit inline interface internal land lor lsl lsr lxor lazy let match member mod module mutable namespace method mixin new not null of open or object override private parallel process protected pure public rec return static sealed struct sig then to true tailcall trait try type upcast use val void virtual volatile when while with yield

Feature	Supported	Token	Example
Binary Literals	✓		// 0[bB][01][01_]*[uU]?[yslLn]?
Integers	✓		// \d[\d_]*[uU]?[yslLnQRZINGmM]?
Floats	✓		// -?\d[\d_](.[\d_])?([eE][+\-]?\d[\d_]*)[fFmM]?
Hexadecimals	✓		// 0[xX][\da-fA-F][\da-fA-F_]*[uU]?[yslLn]?[fF]?
Octals	✓		// 0[oO][0-7][0-7_]*[uU]?[yslLn]?
Conditionals	✓
Access Modifiers	✓
Functions	✓
Constants	✓
Classes	✓
While Loops	✓
Booleans	✓	true false
Strings	✓	"
MultiLine Comments	✓	(* *)	(* A comment *)
Print() Debugging	✓	printfn
Units of Measure	✓		// https://fsharpforfunandprofit.com/posts/units-of-measure/ [] type N = kg m/sec^2 let force1 = 5.0 let force2 = 5.0 force1 = force2 // true
Line Comments	✓	//	// A comment
Type Inference	✓
Semantic Indentation	✓
Operator Overloading	✓
Namespaces	✓		namespace Widgets type MyWidget1 = member this.WidgetName = "Widget1" module WidgetsModule = let widgetName = "Widget2"
File Imports	✓		open module-or-namespace-name open System.IO open List open Seq
Directives	✓		#if VERSION1 let function1 x y = printfn "x: %d y: %d" x y x + 2 * y #else let function1 x y = printfn "x: %d y: %d" x y x - 2*y #endif // Line directives as source maps can be used when compiling to F#: #line 25 "C:\\Projects\\MyProject\\MyProject\\Script1"
Doc comments	✓		/// Adds 2 numbers let rec add x y = x + y
Comments	✓
Case Insensitive Identifiers	X

F#

Language features