[Caml-list] Attn: Development Editor, Latest OCaml Weekly News

[Alan Schmitt <alan.schmitt@polytechnique.org>]

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Hello

Here is the latest OCaml Weekly News, for the week of December 31, 2024
to January 07, 2025.

Table of Contents
─────────────────

Playing with Windows on ARM64
Opam repository archival, Phase 1: unavailable packages
CCL: Categorical Configuration Language
Dune dev meeting
"Cram tests: a hidden gem of dune" and "Snapshot tests for your own ppx"
Other OCaml News
Old CWN


Playing with Windows on ARM64
═════════════════════════════

  Archive:
  <https://discuss.ocaml.org/t/playing-with-windows-on-arm64/15875/1>


David Allsopp announced
───────────────────────

  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…


[Cygwin] <https://cygwin.com>

[my opam fork] <https://github.com/dra27/opam.git>

[windows-on-arm64]
<https://github.com/dra27/opam/commits/windows-on-arm64>


Opam repository archival, Phase 1: unavailable packages
═══════════════════════════════════════════════════════

  Archive:
  <https://discuss.ocaml.org/t/opam-repository-archival-phase-1-unavailable-packages/15797/7>


Continuing this thread, Hannes Mehnert announced
────────────────────────────────────────────────

  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.


Statistics of opam files and unique packages
╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌

  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
   date (January 1st)  opam files  unique packages 
  ─────────────────────────────────────────────────
               phase1       28863             4805 
                 2025       33033             4973 
                 2024       29942             4572 
                 2023       25983             4126 
                 2022       21418             3647 
                 2021       16632             3156 
                 2020       12998             2554 
                 2019       10236             2192 
                 2018        8110             1878 
                 2017        5966             1458 
                 2016        4308             1086 
                 2015        3081              823 
                 2014        1856              593 
                 2013         485              486 
  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  This shows that the amount of opam files are now back to mid-2023,
  while in the unique packages we're in mid-2024.


Next steps
╌╌╌╌╌╌╌╌╌╌

  Next steps and call to action:
  • by January 15th we'll have a list of packages that require OCaml <
    4.08 (plus those packages that were marked unavailable between
    December 15th and January 15th)
  • please mark your packages with [`x-maintenance-intent'] or `flags:
    deprecated'

  On February 15th we will propose a list of packages that are
  deprecated or do not fall into the `x-maintenance-intent' - but only
  if there's no reverse dependency that requires them: if the package
  "cohttp" is marked with `x-maintenance-intent: "(latest)"', and some
  other package "bar" requires a specific cohttp version ('depends:
  "cohttp" {= "1.2.3"}'), the "cohttp.1.2.3" will be kept (to avoid
  making "bar" uninstallable).

  We plan to have tooling ready that allows to spot which packages would
  be beneficial to have a `x-maintenance-intent' or `flags: deprecated'
  (i.e. which ones would allow to archive more packages).

  What is the difference between `flags: deprecated' and
  `x-maintenance-intent'?  Please use `flags: deprecated' if either
  specific versions or an entire package should be archived. Please use
  `x-maintenance-intent' for packages that are actively developed.

  If you have any further questions, please don't hesitate to ask.


[`x-maintenance-intent']
<https://github.com/ocaml/opam-repository/blob/master/governance/policies/archiving.md#specification-of-the-x--fields-used-in-the-archiving-process>


CCL: Categorical Configuration Language
═══════════════════════════════════════

  Archive:
  <https://discuss.ocaml.org/t/ann-ccl-categorical-configuration-language/15901/1>


Dmitrii Kovanikov announced
───────────────────────────

  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>


[chshersh.com: The Most Elegant Configuration Language]
<https://chshersh.com/blog/2025-01-06-the-most-elegant-configuration-language.html>


Dune dev meeting
════════════════

  Archive: <https://discuss.ocaml.org/t/ann-dune-dev-meeting/14994/20>


Etienne Marais announced
────────────────────────

  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:


:calendar: Agenda
╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌

  The agenda is available on the[ meeting dedicated page]. Feel free to
  ask if you want to add more items in it.


[ meeting dedicated page]
<https://github.com/ocaml/dune/wiki/dev-meeting-2025-01-08>


:computer: Links
╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌

  • Meeting link:[ zoom]
  • Calendar event:[ google calendar]
  • Wiki with information and previous notes:[ GitHub Wiki]


[ zoom]
<https://us06web.zoom.us/j/85096877776?pwd=cWNhU1dHQ1ZNSjZuOUZCQ0h2by9Udz09>

[ google calendar]
<https://calendar.google.com/calendar/embed?src=c_5cd698df6784e385b1cdcdc1dbca18c061faa96959a04781566d304dc9ec7319%40group.calendar.google.com>

[ GitHub Wiki] <https://github.com/ocaml/dune/wiki#dev-meetings>


"Cram tests: a hidden gem of dune" and "Snapshot tests for your own ppx"
════════════════════════════════════════════════════════════════════════

  Archive:
  <https://discuss.ocaml.org/t/ann-cram-tests-a-hidden-gem-of-dune-and-snapshot-tests-for-your-own-ppx/15910/1>


David Sancho announced
──────────────────────

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


Cram tests: a hidden gem of dune
╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌

  I'm a strong advocate of unit tests, I can confidently say that it has
  saved me from introducing regressions countless times. Today I want to
  share one of the hidden gems of OCaml and their testing story with
  dune, cram tests.

  <https://sancho.dev/blog/cram-tests-a-hidden-gem-of-dune>


Snapshot tests for your own ppx
╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌

  When building preprocessor extensions (ppx) in OCaml, testing is
  crucial. You want to ensure your ppx works correctly and continues to
  work as you make changes. After experimenting with different
  approaches, I've found that cram tests fit well for the task.

  <https://sancho.dev/blog/snapshot-tests-for-your-own-ppx>

  Let me know what you think, and if there's a need for more :smiley:


Other OCaml News
════════════════

>From the ocaml.org blog
───────────────────────

  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]


[the ocaml.org blog] <https://ocaml.org/blog/>

[What Happened in 2024?]
<https://soap.coffee/~lthms/posts/December2024.html>

[Build A CLI in OCaml with the Cmdliner Library]
<https://debajyatidey.hashnode.dev/build-a-cli-in-ocaml-with-the-cmdliner-library>


Old CWN
═══════

  If you happen to miss a CWN, you can [send me a message] and I'll mail
  it to you, or go take a look at [the archive] or the [RSS feed of the
  archives].

  If you also wish to receive it every week by mail, you may subscribe
  to the [caml-list].

  [Alan Schmitt]


[send me a message] <mailto:alan.schmitt@polytechnique.org>

[the archive] <https://alan.petitepomme.net/cwn/>

[RSS feed of the archives] <https://alan.petitepomme.net/cwn/cwn.rss>

[caml-list] <https://sympa.inria.fr/sympa/info/caml-list>

[Alan Schmitt] <https://alan.petitepomme.net/>


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