There are no fewer than three ports of OCaml for Microsoft Windows, each available in 32 and 64-bit versions:
-
native Windows, built with the Microsoft C/C++ Optimizing Compiler
-
native Windows, built using the Mingw-w64 version of GCC
-
Cygwin (www.cygwin.com)
Here is a summary of the main differences between these ports:
Native Microsoft |
Native Mingw-w64 |
Cygwin |
|
Third-party software required |
|||
for base bytecode system |
none |
none |
none |
for |
Microsoft Visual C++ |
Cygwin |
Cygwin |
for native-code generation |
Microsoft Visual C++ |
Cygwin |
Cygwin |
Features |
|||
Speed of bytecode interpreter |
70% |
100% |
100% |
Replay debugger |
yes (**) |
yes (**) |
yes |
The Unix library |
partial |
partial |
full |
The Threads library |
yes |
yes |
yes |
The Graphics library |
yes |
yes |
no |
Restrictions on generated executables? |
none |
none |
yes (*) |
- (*)
-
Executables generated by the native GCC package in Cygwin are linked with the Cygwin DLL and require this to be distributed with your programs. Executables generated by Microsoft Visual C or the Mingw-w64 compilers (even when run in Cygwin as `i686-w64-mingw32-gcc` or `x86_64-w64-mingw32-gcc`) are not linked against this DLL. Prior to Cygwin 2.5.2 (the Cygwin version can be obtained with `uname -r`) the Cygwin DLL is distributed under the GPL, requiring any programs linked with it to be distributed under a compatible licence. Since version 2.5.2, the Cygwin DLL is distributed under the LGPLv3 with a static linking exception meaning that, like executables generated by Microsoft Visual C or the Mingw-w64 compilers, generated executables may be distributed under terms of your choosing.
- (**)
-
The debugger is supported but the "replay" functions are not enabled. Other functions are available (step, goto, run…).
Cygwin aims to provide a Unix-like environment on Windows, and the build procedure for it is the same as for other flavours of Unix. See INSTALL.adoc for full instructions.
The native ports require Windows XP or later and naturally the 64-bit versions need a 64-bit edition of Windows (note that this is both to run and build).
The two native Windows ports have to be built differently, and the remainder of this document gives more information.
All the Windows ports require a Unix-like build environment. Although other methods are available, the officially supported environment for doing this is 32-bit (x86) Cygwin.
Only the make
Cygwin package is required. diffutils
is required if you wish
to be able to run the test suite.
Unless you are also compiling the Cygwin port of OCaml, you should not install
the gcc-core
or flexdll
packages. If you do, care may be required to ensure
that a particular build is using the correct installation of flexlink
.
In addition to Cygwin, FlexDLL must also be installed, which is available from
https://github.com/alainfrisch/flexdll. A binary distribution is available;
instructions on how to build FlexDLL from sources, including how to bootstrap
FlexDLL and OCaml are given later in this document. Unless you
bootstrap FlexDLL, you will need to ensure that the directory to which you
install FlexDLL is included in your PATH
environment variable. Note: if you
use Visual Studio 2015 or Visual Studio 2017, the binary distribution of
FlexDLL will not work and you must build it from sources.
The base bytecode system (ocamlc, ocaml, ocamllex, ocamlyacc, …) of all three ports runs without any additional tools.
The native-code compiler (ocamlopt
) and static linking of OCaml bytecode with
C code (ocamlc -custom
) require a Microsoft Visual C/C++ Compiler and the
flexlink
tool (see above).
Any edition (including Express/Community editions) of Microsoft Visual Studio 2005 or later may be used to provide the required Windows headers and the C compiler. Additionally, some older Microsoft Windows SDKs include the Visual C/C++ Compiler.
|
Express |
SDK |
|
Visual Studio 2005 |
14.00.x.x |
32-bit only (*) |
|
Visual Studio 2008 |
15.00.x.x |
32-bit only |
Windows SDK 7.0 also provides 32/64-bit compilers |
Visual Studio 2010 |
16.00.x.x |
32-bit only |
Windows SDK 7.1 also provides 32/64-bit compilers |
Visual Studio 2012 |
17.00.x.x |
32/64-bit |
|
Visual Studio 2013 |
18.00.x.x |
32/64-bit |
|
Visual Studio 2015 |
19.00.x.x |
32/64-bit |
|
Visual Studio 2017 |
19.10.x.x |
32/64-bit |
- (*)
-
Visual C++ 2005 Express Edition does not provide an assembler; this can be downloaded separately from https://www.microsoft.com/en-gb/download/details.aspx?id=12654
The command-line tools must be compiled from the Unix source distribution
(ocaml-X.YY.Z.tar.gz
), which also contains the files modified for Windows.
(Note: you should use cygwin’s tar
command to unpack this archive. If you
use WinZip, you will need to deselect "TAR file smart CR/LF conversion" in
the WinZip Options Window.)
Microsoft Visual C/C++ is designed to be used from special developer mode Command Prompts which set the environment variables for the required compiler. There are multiple ways of setting up your environment ready for their use. The simplest is to start the appropriate command prompt shortcut from the program group of the compiler you have installed.
The details differ depending on whether you are using a Windows SDK to provide the compiler or Microsoft Visual Studio itself.
For the Windows SDK, there is only one command prompt called "CMD Shell" in
versions 6.1 and 7.0 and "Windows SDK 7.1 Command Prompt" in version 7.1. This
launches a Command Prompt which will usually select a DEBUG
build environment
for the operating system that you are running. You should then run:
SetEnv /Release /x86
for 32-bit or:
SetEnv /Release /x64
for 64-bit. For Visual Studio 2005-2013, you need to use one of the shortcuts in the "Visual Studio Tools" program group under the main program group for the version of Visual Studio you installed. For Visual Studio 2015 and 2017, you need to use the shortcuts in the "Windows Desktop Command Prompts" (2015) or "VC" (2017) group under the "Visual Studio Tools" group.
Unlike SetEnv
for the Windows SDK, the architecture is selected by using a
different shortcut, rather than by running a command.
For Visual Studio 2005-2010, excluding version-specific prefixes, these are named "Command Prompt" for 32-bit and "x64 Cross Tools Command Prompt" or "x64 Win64 Command Prompt" for 64-bit. It does not matter whether you use a "Cross Tools" or "Win64" version for x64, this simply refers to whether the compiler itself is a 32-bit or 64-bit program; both produce 64-bit output and work with OCaml.
For Visual Studio 2012 and 2013, both x86 and x64 Command Prompt shortcuts indicate if they are the "Native Tools" or "Cross Tools" versions. Visual Studio 2015 and 2017 make the shortcuts even clearer by including the full name of the architecture.
You cannot at present use a cross-compiler to compile 64-bit OCaml on 32-bit Windows.
Once you have started a Command Prompt, you can verify that you have the compiler you are expecting simply by running:
cl Microsoft (R) C/C++ Optimizing Compiler Version 19.00.23506 for x86 ...
You then need to start Cygwin from this Command Prompt. Assuming you have
installed it to its default location of C:\cygwin
, simply run:
C:\cygwin\bin\mintty -
(note the space and hyphen at the end of the command).
This should open a terminal window and start bash. You should be able to run
cl
from this. You can now change to the top-level directory of the directory
of the OCaml distribution.
The Microsoft Linker is provided by a command called link
which unfortunately
conflicts with a Cygwin command of the same name. It is therefore necessary to
ensure that the directory containing the Microsoft C/C++ Compiler appears at
the beginning of PATH
, before Cygwin’s /usr/bin
. You can automate this from
the top-level of the OCaml distribution by running:
eval $(tools/msvs-promote-path)
If you forget to do this, make world
will fail relatively
quickly as it will be unable to link ocamlrun
.
Now run:
cp config/m-nt.h byterun/caml/m.h cp config/s-nt.h byterun/caml/s.h
followed by:
cp config/Makefile.msvc config/Makefile
for 32-bit, or:
cp config/Makefile.msvc64 config/Makefile
for 64-bit. Then, edit config/Makefile
as needed, following the comments in
this file. Normally, the only variable that needs to be changed is PREFIX
,
which indicates where to install everything.
Finally, use make
to build the system, e.g.
make world bootstrap opt opt.opt install
After installing, it is not necessary to keep the Cygwin installation (although
you may require it to build additional third party libraries and tools). You
will need to use ocamlopt
(or ocamlc -custom
) from the same Visual Studio or
Windows SDK Command Prompt as you compiled OCaml from, or ocamlopt
will not
be able to find cl
.
If you wish to use ocamlopt
from Cygwin’s bash on a regular basis, you may
like to copy the tools/msvs-promote-path
script and add the eval
line to
your ~/.bashrc
file.
-
The Microsoft Visual C/C++ compiler does not implement "computed gotos", and therefore generates inefficient code for
byterun/interp.c
. Consequently, the performance of bytecode programs is about 2/3 of that obtained under Unix/GCC, Cygwin or Mingw-w64 on similar hardware. -
Libraries available in this port:
bigarray
,dynlink
,graphics
,num
,str
,threads
, and large parts ofunix
. -
The replay debugger is partially supported (no reverse execution).
The native-code compiler (ocamlopt
) and static linking of OCaml bytecode with
C code (ocamlc -custom
) require the appropriate Mingw-w64 gcc and the
flexlink
tool (see above). Mingw-w64 gcc is provided by the
mingw64-i686-gcc-core
package for 32-bit and the mingw64-x86_64-gcc-core
package for 64-bit.
-
Do not try to use the Cygwin version of flexdll for this port.
-
The standalone mingw toolchain from the Mingw-w64 project (http://mingw-w64.org/) is not supported. Please use the version packaged in Cygwin instead.
The command-line tools must be compiled from the Unix source distribution
(ocaml-X.YY.Z.tar.gz
), which also contains the files modified for Windows.
(Note: you should use cygwin’s tar
command to unpack this archive. If you
use WinZip, you will need to deselect "TAR file smart CR/LF conversion" in
the WinZip Options Window.)
Now run:
cp config/m-nt.h byterun/caml/m.h cp config/s-nt.h byterun/caml/s.h
followed by:
cp config/Makefile.mingw config/Makefile
for 32-bit, or:
cp config/Makefile.mingw64 config/Makefile
for 64-bit. Then, edit config/Makefile
as needed, following the comments in
this file. Normally, the only variable that needs to be changed is PREFIX
,
which indicates where to install everything.
Finally, use make
to build the system, e.g.
make world bootstrap opt opt.opt install
After installing, you will need to ensure that ocamlopt
(or ocamlc -custom
)
can access the C compiler. You can do this either by using OCaml from Cygwin’s
bash or by adding Cygwin’s bin directory (e.g. C:\cygwin\bin
) to your PATH
.
-
Libraries available in this port:
bigarray
,dynlink
,graphics
,num
,str
,threads
, and large parts ofunix
. -
The replay debugger is partially supported (no reverse execution).
-
The default
config/Makefile.mingw
andconfig/Makefile.mingw64
pass-static-libgcc
to the linker. For more information on this topic:
Although the core of FlexDLL is necessarily written in C, the flexlink
program
is, naturally, written in OCaml. This creates a circular dependency if you wish
to build entirely from sources. Since OCaml 4.03 and FlexDLL 0.35, it is now
possible to bootstrap the two programs simultaneously. The process is identical
for both ports. If you choose to compile this way, it is not necessary to
install FlexDLL separately — indeed, if you do install FlexDLL separately, you
may need to be careful to ensure that ocamlopt
picks up the correct flexlink
in your PATH
.
You must place the FlexDLL sources for Version 0.35 or later in the directory
flexdll/
at the top-level directory of the OCaml distribution. This can be
done in one of three ways:
-
Extracting the sources from a tarball from https://github.com/alainfrisch/flexdll/releases
-
Cloning the git repository by running:
git clone https://github.com/alainfrisch/flexdll.git
-
If you are compiling from a git clone of the OCaml repository, instead of using a sources tarball, you can run:
git submodule update --init
OCaml is then compiled as normal for the port you require, except that before
compiling world
, you must compile flexdll
, i.e.:
make flexdll world [bootstrap] opt opt.opt install
-
make install
will install FlexDLL by placingflexlink.exe
(and the default manifest file for the Microsoft port) inbin/
and the FlexDLL object files inlib/
. -
If you don’t include
make opt.opt
,flexlink.exe
will be a bytecode program.make install
always installs the "best"flexlink.exe
(i.e. there is never aflexlink.opt.exe
installed). -
If you have populated
flexdll/
, you must runmake flexdll
. If you wish to revert to using an externally installed FlexDLL, you must erase the contents offlexdll/
before compiling.