OCaml Weekly News

Following on from the teaser in https://discuss.ocaml.org/t/arm-windows-installation-as-of-today/15697/4, if you're lucky enough to have an ARM64 Windows machine, it's just about possible to get a few opam packages installed and working it!

You'll need Visual Studio 2022 (Community) with the following packages:

• MSVC v143 - VS 2022 C++ ARM64/ARM64EC build tools (Latest)
• MSVC v143 - VS 2022 C++ x64/x86 build tools (Latest)
• C++/CLI support for v143 build tools (Latest)
• C++ Clang Compiler for Windows (18.1.8)

That's not a typo: you need Clang and both the x64/x86 and ARM64 MSVC packages

Install Git for Windows as normal (winget install Git.Git, etc.) and Cygwin (adding the make and patch packages - no compilers or libraries needed, it's just to get the shell).

Clone my opam fork and check out branch windows-on-arm64. From a Cygwin bash terminal, cd to that clone and run make cold. After a little while, that should leave an ARM64 opam.exe in the current directory which should be copied to a location which you then add to PATH.

From Cmd/PowerShell, you can now run:

PS > opam init --bare
PS > opam switch create --empty windows-on-arm64
PS > opam pin add --yes ocaml-variants git+https://github.com/dra27/ocaml.git#windows-on-arm64

Dune needs a trivial pin (which I think may be more to do with a recent Windows SDK issue, than arm64-specific):

PS > opam pin add dune git+https://github.com/dra27/dune.git#windows-on-arm64

Unfortunately, it's not quite enough to get opam's dependencies installing through opam (dose3 failed for me, which is odd because it works with make cold and topkg was freezing, although that's less surprising). But it's kinda cool how much is working straightaway, and it certainly looks like we'll have native Windows ARM64 support at some point in the future, therefore!

Aside from the usual "packages which don't work properly" issue, there're two glaring problems:

1. It should be possible to install the x86 / x64 compilers, but at present this doesn't work because the opam compiler packages need further tweaking[^1]
2. Only Clang-pretending-to-be-cl is supported at the moment - I can't see any reason that Clang-pretending-to-be-gcc shouldn't be doable, but as we don't presently support that for x64 either (and it necessarily needs MSYS2, rather than Cygwin), I haven't disappeared down that rabbit hole yet[^2]

:warning: I have no timeline for upstreaming any of this, but it's all publicly pushed and welcome to anyone to extend to a mergeable state!

[^1]: I'll likely get to that at some point soon, as that unblocks general use of OCaml on Windows ARM64 machines, even if not native ARM64 use. However, it exceeds "fun messing around over Christmas and New Year"!

[^2]: See 1…

It's done. It's done. It's done.

Happy new year!

We just merged the removal of the above mentioned uninstallable packages from opam-repository. In case you want to get these old opam files, please use:

opam repository add opam-archive https://github.com/ocaml/opam-repository-archive.git

Each of the opam files now include the two additional fields: (a) a x-reason-for-archival and (b) an x-opam-repository-commit-hash-at-time-of-archiving (as described in https://github.com/ocaml/opam-repository/blob/master/governance/policies/archiving.md#specification-of-the-x--fields-used-in-the-archiving-process).

We also pushed the tag '2025-01-before-archiving-phase1' to the main opam-repository.

Hi everyone :wave:

For the last month, I've been working on a hobby project, shaping years of my ideas into the implementation of minimalistic config language ccl: Categorical Configuration Language.

You can read the motivation and a tutorial in my latest article:

• chshersh.com: The Most Elegant Configuration Language

I implemented CCL in OCaml using angstrom. The source code is here:

• https://github.com/chshersh/ccl

Hi :wave:

We will hold our first Dune dev meeting of 2025 (Happy New Year :partying_face:) on Wednesday, January, 8th at 9:00 CET. As usual, the session will be one hour long.

Whether you are a maintainer, a regular contributor, a new joiner or just curious, you are welcome to join: these discussions are opened! The goal of these meetings is to provide a place to discuss the ongoing work together and synchronize between the Dune developers ! :camel:

Hi, I wrote 2 blog posts about cram tests and It's a good idea to share them together.

Here are links from many OCaml blogs aggregated at the ocaml.org blog.

• What Happened in 2024?
• Build A CLI in OCaml with the Cmdliner Library