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The official windows installer (built using NSIS) for OCaml
NSIS OCaml Makefile Emacs Lisp
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The OCaml Installer for Windows

These are the source files if you want to rebuild the installer. If you just want to download the installer, see the "website" link near the top of the page.

The installer now uses the "official" toolchain, namely Mingw64 living in a Cygwin environment. The current version of this installer works with OCaml 4.0; if you want to compile an older version of OCaml, you need to switch to and older revision.


  • Cygwin with the mingw64 compiler suite, 32bit version (i686-w64-mingw32).
  • FlexDLL (at least 0.27)
  • NSIS
  • the NSISunz plugin for NSIS, that lives somewhere on the NSIS wiki


The instructions above sometimes use the c:\...-style paths, sometimes the /c/...-style paths. This is significant, and you cannot blindly replace one for another.

  1. Install FlexDLL from Alain's website, and
    • export PATH=/cygdrive/c/path/to/flexdll:$PATH
    • export FLEXLINKFLAGS="-Lc:/cygwin/usr/i686-w64-mingw32/sys-root/mingw/lib/ -Lc:/cygwin/lib/gcc/i686-w64-mingw32/N.N.N/" where N.N.N is the version of GCC that ships with your Cygwin setup.
  2. Refresh the files in the flexdll/ directory of the installer, so that the resulting installer ships the right version of flexdll.
  3. Grab a copy of ActiveTCL and install it, leave the default path (c:\tcl).
  4. Grab a copy of the OCaml sources, and keep the default install path (c:\ocamlmgw), this will make your life easier.
  5. Follow the instructions in README.Win32, section "MinGW/Cygwin". Try to compile OCaml. Swear. Try again. Grab a tea. Succeed. Be happy.
  6. Go into the emacs/ directory.
    • Make sure there's an emacs.exe in your path (install Emacs if you have to).
    • Configure the Makefile so that the output directory is /c/ocamlmgw/emacsfiles.
    • Run make in that directory.
  7. Install NSIS, grab nsisunz.dll somewhere on the interwebs and put it NSIS's Plugins directory.
  8. Make sure /c/ocamlmgw/bin is in your path.
  9. In the ocaml-installer directory (i.e. this repo), run make. This should create a variety of files:
    • version.nsh, a NSIS header file that is generated to contain the freshly compiled OCaml's version number,
    • uninstall_lines.nsi, an OCaml-generated list of files to remove from the install directory.
  10. Make should also launch NSIS with the main script file, and hopefully it should all generate an installer. The installer is quite big (thank you camlp4).

Bugs, issues

All patches should be submitted using GitHub pull requests. All issues should be filed using the GitHug issue tracker.

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