Caution

The developer team released OCaml 5.0.0 in December 2022. OCaml 5.x features a full rewrite of its runtime system for shared-memory parallel programming using domains and native support for concurrent programming using effect handlers. Owing to the large number of changes, especially to the garbage collector, OCaml 4.14 (the final release in the OCaml 4.x series, originally released in March 2022) remains supported for the time being. Maintainers of existing codebases are strongly encouraged to evaluate OCaml 5.x and to report any performance degradations on our issue tracker.

Branch trunk	Branch 5.3	Branch 5.2	Branch 5.1	Branch 4.14

README

Overview

OCaml is a functional, statically-typed programming language from the ML family, offering a powerful module system extending that of Standard ML and a feature-rich, class-based object system.

OCaml comprises two compilers. One generates bytecode which is then interpreted by a C program. This compiler runs quickly, generates compact code with moderate memory requirements, and is portable to many 32 or 64 bit platforms. Performance of generated programs is quite good for a bytecoded implementation. This compiler can be used either as a standalone, batch-oriented compiler that produces standalone programs, or as an interactive REPL system.

The other compiler generates high-performance native code for a number of processors. Compilation takes longer and generates bigger code, but the generated programs deliver excellent performance, while retaining the moderate memory requirements of the bytecode compiler. The native-code compiler currently runs on the following platforms:

	Tier 1 (actively maintained)	Tier 2 (maintained when possible)
x86 64 bits	Linux, macOS, Windows, FreeBSD	NetBSD, OpenBSD, OmniOS (Solaris)
ARM 64 bits	Linux, macOS	FreeBSD, OpenBSD, NetBSD
Power 64 bits	Linux (little-endian, ABIv2)	Linux (big-endian, ABIv2)
RISC-V 64 bits	Linux
IBM Z (s390x)	Linux

Other operating systems for the processors above have not been tested, but the compiler may work under other operating systems with little work.

❗ From OCaml 5.0 onwards, native compilation is available only on 64-bit systems. Native compilation on 32-bit systems is no longer available, nor are there plans to bring it back.

Copyright

All files marked "Copyright INRIA" in this distribution are Copyright © 1996-2023 Institut National de Recherche en Informatique et en Automatique (INRIA) and distributed under the conditions stated in file LICENSE.

Installation

See the file INSTALL.adoc for installation instructions on machines running Unix, Linux, macOS, WSL and Cygwin. For native Microsoft Windows, see README.win32.adoc.

Documentation

The OCaml manual is distributed in HTML, PDF, and Emacs Info files. It is available at

https://ocaml.org/manual/latest/

Availability

The complete OCaml distribution can be accessed at

https://ocaml.org/docs/install.html

Releases

More information about when and how new releases of OCaml are published is available at release-info/introduction.md, see also release-info/calendar.md for a prospective calendar for future OCaml versions. For past versions, release-info/News contains a short description of major changes in previous versions.

Keeping in Touch with the Caml Community

There is an active and friendly discussion forum at

https://discuss.ocaml.org/

The OCaml mailing list is the longest-running forum for OCaml users. You can email it at

caml-list@inria.fr

You can subscribe and access list archives via the Web interface at

https://sympa.inria.fr/sympa/subscribe/caml-list

There also exist other mailing lists, chat channels, and various other forums around the internet for getting in touch with the OCaml and ML family language community. These can be accessed at

https://ocaml.org/community/

In particular, the IRC channel #ocaml on Libera has a long history and welcomes questions.

Bug Reports and User Feedback

Please report bugs using the issue tracker at https://github.com/ocaml/ocaml/issues

To be effective, bug reports should include a complete program (preferably small) that exhibits the unexpected behavior, and the configuration you are using (machine type, etc).

Contributing

For information on contributing to OCaml, see HACKING.adoc and CONTRIBUTING.md.

Separately maintained components

Some libraries and tools which used to be part of the OCaml distribution are now maintained separately and distributed as OPAM packages. Please use the issue trackers at their respective new homes:

Library	Removed since	OPAM package
The Stream and Genlex standard library modules	OCaml 5.0	camlp-streams
The Graphics library	OCaml 4.09	graphics
The Num library	OCaml 4.06	num
The OCamlbuild tool	OCaml 4.03	ocamlbuild
The camlp4 tool	OCaml 4.02	camlp4
The LablTk library	OCaml 4.02	labltk
The CamlDBM library	OCaml 4.00	dbm
The OCamlWinTop Windows toplevel	OCaml 4.00	none