⚠️ CAUTION

The developer team released OCaml 5.0.0 in December 2022. This release sports 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, the initial 5.0 release is more experimental than usual. It is recommended that all users wanting a stable release use the 4.14 release which will continue to be supported and updated while 5.x reaches feature and stability parity. Similarly, if you need one of the ports not yet supported in the 5.0 release you must use the 4.14 release.

The initial release of OCaml 5.0 only supports the native compiler under ARM64 and x86-64 architectures under Linux, macOS and the BSDs. On Windows, only the MinGW-w64 port is supported in OCaml 5.0 and the Cygwin port is restored in 5.1. On Linux, native code support for RISC-V and s390x/IBM Z will be available in OCaml 5.1 and on Power in 5.2.

❗ 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. The bytecode compiler will continue to work on all architectures.

Branch trunk	Branch 5.1	Branch 5.0	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.

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/releases/latest/manual.html

Availability

The complete OCaml distribution can be accessed at

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

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

[email protected]

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).

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