OCaml - Programming language

OCaml is an open source programming language created in 1996 by Xavier Leroy.

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OCaml ( oh-KAM-əl), originally named Objective Caml, is the main implementation of the programming language Caml, created by Xavier Leroy, Jérôme Vouillon, Damien Doligez, Didier Rémy, Ascánder Suárez and others in 1996. A member of the ML language family, OCaml extends the core Caml language with object-oriented programming constructs. OCaml's toolset includes an interactive top-level interpreter, a bytecode compiler, a reversible debugger, a package manager (OPAM), and an optimizing native code compiler. Read more on Wikipedia...

Tags: programming language
There are at least 27,376 OCaml repos on GitHub
Early development of OCaml happened in Inria
The Google BigQuery Public Dataset GitHub snapshot shows 4k users using OCaml in 6k repos on GitHub
Check out the 87 OCaml meetup groups on Meetup.com.
There are 219 Project Euler users using OCaml
Explore OCaml snippets on Rosetta Code
OCaml on HOPL
OCaml appears in the TIOBE Index
OCaml Ubuntu package
Pygments supports syntax highlighting for OCaml
GitHub supports syntax highlighting for OCaml
OCaml appears in the Quine Relay project
Learn OCaml on exercism.
PLDB has 2 Jupyter Kernels for OCaml: github.com, github.com
There is a central package repository for OCaml
ocaml.org was registered in 2000
See also: (36 related languages) Occam, C, IA-32, SPARC, ARM, Unix, F#, Caml, Classroom Object Oriented Language, Standard ML, ATS, Elm, F*, Haxe, Opa, Rust, Scala, ML, Python, Perl, Java, C#, Fortran, JavaScript, JVM, PIC microcontroller, Emacs, Vim, OpenGL, Hack, PHP, iOS, Android, Coq, WebAssembly, Haskell
51 PLDB concepts link to OCaml: Ace Editor, atomspace, Austral, bamboo, Bucklescript, Caml, Caramel, Catala, CIR, cloc, comby, Coq, datafun, dedukti, eff, Elpi, FaCT, Felix, Flow, Flow9, F*, gintonic, Haxe, Hazel, HHVM, IPL, juvix, Koka, Ligo, LinearML, Links, mal, MLscript, Neko, Not Quite C, Opa, opam-pm, psyche, Pygments, Ragel, ramen, Reason, SATySFi, silk, sill, skip, Slick, Semantic Patch Language, Umka, Vale, xs

Example from Compiler Explorer:

let square x = x * x

Example from Riju:

;;
print_string "Hello, world!\n"

Example from hello-world:

print_string "Hello World\n"

Example from the Hello World Collection:

(* Hello World in OCaml *)
print_string "Hello World!\n";;

Example from Linguist:

(*
 * Copyright (c) 2013 Jeremy Yallop.
 *
 * This file is distributed under the terms of the MIT License.
 * See the file LICENSE for details.
 *)
let string_of format v =
  let buf = Buffer.create 100 in
  let fmt = Format.formatter_of_buffer buf in begin
    format fmt v;
    Format.pp_print_flush fmt ();
    Buffer.contents buf
  end

Example from Wikipedia:

fun x_1 -> (x_1 *
     let y_3 =
         let y_2 = (x_1 * 1)
         in (y_2 * y_2)
     in (y_3 * y_3))

OCaml Keywords

as assert begin class constraint do done downto else end exception external false for fun function functor if in include inherit initializer lazy let match method module mutable new object of open private raise rec sig struct then to true try type value val virtual when while with

Language features

Feature	Supported	Example	Token
Binary Literals	✓
Integers	✓
Floats	✓
Hexadecimals	✓
Octals	✓
Conditionals	✓
Functions	✓
Classes	✓
While Loops	✓
Booleans	✓		true false
Print() Debugging	✓		print_string
MultiLine Comments	✓	(* A comment *)	(* *)
Module Pattern	✓	(* In OCaml, every piece of code is wrapped into a module. ) ( amodule.ml ) let hello () = print_endline "Hello" ( bmodule.ml *) Amodule.hello ()
Type Inference	✓
Multiple Inheritance	✓
Comments	✓	(* This is a single-line comment. ) ( This is a * multi-line * comment. *)
Case Insensitive Identifiers	X
Semantic Indentation	X
Line Comments	X