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📢 Note 📢

Multicore OCaml project has now been merged into OCaml 🎉. This repository is no longer developed or maintained. Please follow the updates at the OCaml Github repository.

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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


x86 32 bits

Linux, Windows

FreeBSD, NetBSD, OpenBSD

ARM 64 bits

Linux, macOS


ARM 32 bits


FreeBSD, NetBSD, OpenBSD

Power 64 bits


Power 32 bits


RISC-V 64 bits


IBM Z (s390x)


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

All files marked "Copyright INRIA" in this distribution are Copyright © 1996-2021 Institut National de Recherche en Informatique et en Automatique (INRIA) and distributed under the conditions stated in file LICENSE.


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.


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


The complete OCaml distribution can be accessed at

Keeping in Touch with the Caml Community

There is an active and friendly discussion forum at

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

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

An alternative archive of the mailing list is also available at

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

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

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

Separately maintained components

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