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OCaml 3.12.1

This page describes OCaml version 3.12.1, released on 2011-07-04.

The OCaml system is open source software: the compiler is distributed under the terms of the Q Public License, and its library is under LGPL; please read the license document for more details. A BSD-style license is also available for a fee through the OCaml Consortium.

What's New

Some of the highlights in release 3.12 are:

  • Polymorphic recursion is supported, using explicit type declarations on the recursively-defined identifiers.
  • First-class modules: module expressions can be embedded as values of the core language, then manipulated like any other first-class value, then projected back to the module level.
  • New operator to modify a signature a posteriori: S with type t := tau denotes signature S where the t type component is removed and substituted by the type tau elsewhere.
  • New notations for record expressions and record patterns: { lbl } as shorthand for { lbl = lbl }, and { ...; _ } marks record patterns where some labels were intentionally omitted.
  • Local open let open ... in ... now supported by popular demand.
  • Type variables can be bound as type parameters to functions; such types are treated like abstract types within the function body, and like type variables (possibly generalized) outside.
  • The module type of construct enables to recover the module type of a given module.
  • Explicit method override using the method! keyword, with associated warnings and errors.

For more information, please consult the comprehensive list of changes.

Source distribution

  • Source tarball (.tar.gz) for compilation under Unix (including Linux and MacOS X) and Microsoft Windows (including Cygwin).
  • Also available in .zip format.
  • You also have access to the working sources and to all previous public releases.

The INSTALL file of the distribution provides detailed compilation and installation instruction.

Precompiled binaries for FreeBSD

Use binary packages provided by the FreeBSD project. Further information about the FreeBSD packages is available at FreshPorts.

Precompiled binaries for Linux

Precompiled binaries for MacOS X

Binary package compiled on Mac OS 10.6.4 with XCode tools 3.2.3 (not compatible with Mac OS 10.4.x):

Precompiled binaries for Microsoft Windows

Four ports of OCaml for Microsoft Windows are currently available. For additional information, please consult the list of portability issues or the Windows release notes.

  • MinGW-based native Win32 port (3.12.1). A self installer. The interactive loop comes with a simple graphical user interface. Some features require the Cygwin environment. However, the compilers generate true Win32 executables, which do not require Cygwin to run.
  • Cygwin-based port. Requires Cygwin. No graphical user interface is provided. The compilers generate executables that do require Cygwin. The precompiled binaries are part of the Cygwin distribution; you can install them using the Cygwin setup tool. Alternatively, download the source distribution and compile it under Cygwin.
  • Microsoft-based native Win64 port Same features as the Microsoft-based native Win32 port, but generates 64-bit code. No binary distribution available yet; download the source distribution and compile it.

Precompiled binaries for Solaris

Available at

User's manual

The user's manual for OCaml can be: