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

Alan Schmitt
2025-03-18T10:19:01Z

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Hello

Here is the latest OCaml Weekly News, for the week of March 11 to 18,
2025.

Table of Contents
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Upgrading Semgrep from OCaml 4 to OCaml 5 + dynamic_gc utility
Open source OCaml algotrading with longleaf 1.0.0
Neocaml - a TreeSitter-powered Emacs package for OCaml programming
Senior Software Engineer at Bloomberg. New York
Upcoming Cmdliner 2.0 changes that need your attention
Dune dev meeting
New release of Monolith (20250314)
dream_middleware_ext v0.1.0
Learn Programming with OCaml (new book)
Other OCaml News
Old CWN

Upgrading Semgrep from OCaml 4 to OCaml 5 + dynamic_gc utility
══════════════════════════════════════════════════════════════

Archive:
<https://discuss.ocaml.org/t/upgrading-semgrep-from-ocaml-4-to-ocaml-5-dynamic-gc-utility/16256/1>

Nat Mote announced
──────────────────

I've written up my experience [upgrading Semgrep to OCaml 5]. The main
barrier we faced was increased memory consumption, but I was able to
tune the garbage collector to address this problem. We have also
open-sourced the [utility I wrote] to adjust the `space_overhead' GC
parameter based on heap size. We are looking forward to taking
advantage of all the great new features in OCaml 5!

[upgrading Semgrep to OCaml 5]
<https://semgrep.dev/blog/2025/upgrading-semgrep-from-ocaml-4-to-ocaml-5/>

[utility I wrote] <https://github.com/semgrep/dynamic-gc>

Open source OCaml algotrading with longleaf 1.0.0
═════════════════════════════════════════════════

Archive:
<https://discuss.ocaml.org/t/open-source-ocaml-algotrading-with-longleaf-1-0-0/16264/1>

adventure announced
───────────────────

Recently, I have been working on a project called [longleaf] for
algorithmic trading of US stocks with OCaml. The project has reached
a point where it may be interesting to others, so I thought I would
share it here and write a simple README, although there could be a lot
more documentation. I would be curious to hear if anyone has any
ideas for this! If you try to use it or have any feedback or
questions, feel free to leave a post here, make a github issue, or
make a github discussion.

In a nutshell, the idea is that strategies are functors that are
instantiated with a "backend" for backtesting, live, or paper trading.
That way, whether you are testing your strategy or running it live, it
is exactly the same strategy other than how the execution of orders is
handled. In order to use it, you will need to set up some accounts
and there are likely bugs. Of course, if you use this program with
real money and something bad happens, it is entirely your
responsibility!

[github]

[longleaf] <https://github.com/hesterjeng/longleaf>

[github] <https://github.com/hesterjeng/longleaf>

Neocaml - a TreeSitter-powered Emacs package for OCaml programming
══════════════════════════════════════════════════════════════════

Archive:
<https://discuss.ocaml.org/t/neocaml-a-treesitter-powered-emacs-package-for-ocaml-programming/16268/1>

Bozhidar Batsov announced
─────────────────────────

In a different topics I wrote about about my recent work on neocaml,
and I thought it might be a good idea to post something separately as
well. Check out the project's GitHub [repo] and the short [blog post].

Contributions and feedback are most welcome, and I hope `neocaml' will
be useful to some of you either a tool or as a source of inspiration.

[repo] <https://github.com/bbatsov/neocaml>

[blog post]
<https://batsov.com/articles/2025/03/14/neocaml-a-new-emacs-package-for-ocaml-programming/>

Senior Software Engineer at Bloomberg. New York
═══════════════════════════════════════════════

Archive:
<https://discuss.ocaml.org/t/senior-software-engineer-at-bloomberg-new-york/16271/1>

Maxim Grankin announced
───────────────────────

Hi everyone! 👋

Bloomberg is looking for a full-time Senior Software Engineer in New
York:

• Gain experience applying functional programming to real production
financial systems
• Use OCaml to develop a robust template system to assist users in
creating a wide range of financial instruments across various asset
classes
• Help shape the strategy for growth of OCaml at Bloomberg by
contributing to the various OCaml infrastructure projects across the
company
• Opportunity to learn some of the financial domain that's at the core
of the extensive derivative functionality

Please see more details and/or apply at [(Senior Software Engineer -
Functional Programming)].

Feel free to reach out to me directly by email
(mgrankin@bloomberg.net) if you have any questions. Thank you!

[(Senior Software Engineer - Functional Programming)]
<https://bloomberg.avature.net/careers/JobDetail?jobId=10730&qtvc=272d0d0846f74b19dc66d7fdc29cec05a0ad67e646ae6c1e1cb94f5ae1c9c4c2#>

Upcoming Cmdliner 2.0 changes that need your attention
══════════════════════════════════════════════════════

Archive:
<https://discuss.ocaml.org/t/upcoming-cmdliner-2-0-changes-that-need-your-attention/16211/2>

Continuing this thread, Daniel Bünzli announced
───────────────────────────────────────────────

Other [changes] you may want to pay attention to is that cmdliner 2.0
will:

1. Remove deprecated identifiers.
2. Make the [`Arg.conv'] type abstract[^1].

If you happen to be walking around your `cmdliner' usage or making a
new cli these days, pay particular attention to 2. as the concrete
type has been deprecated since 2017 but sadly it was never possible to
make it a visible deprecation (OCaml compiler help us! :man_bowing:).

Note that both 1. and 2. can be resolved now by using cmdliner.1.3.0,
there are a few [instructions here]. It's no guaranteed, but if you
are on `opam' I may have filed an issue in your issue tracker
:waving_hand:.

P.S. I think there's not a single occurence where I did not eventually
regret making a public type concrete.

[^1]: So that completion behaviours can be defined at that level;
aswell as the documentation metavariable which you could specify with
`Arg.conv' constructors for ages but would simply be dropped to return
the concrete pair.

[changes] <https://github.com/dbuenzli/cmdliner/issues/206>

[`Arg.conv']
<https://erratique.ch/software/cmdliner/doc/Cmdliner/Arg/index.html#type-conv>

[instructions here] <https://github.com/dbuenzli/cmdliner/issues/206>

Dune dev meeting
════════════════

Archive: <https://discuss.ocaml.org/t/ann-dune-dev-meeting/14994/26>

Etienne Marais announced
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Hi! The next Dune Dev Meeting will be on *Wednesday, March, 19th at
16:00 CET*. This is going to be a one-hour-long meeting.

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 with the Dune developers :+1:

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

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

[meeting dedicated page]
<https://github.com/ocaml/dune/wiki/dev-meeting-2025-03-19>

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

[google calendar]
<https://calendar.google.com/calendar/u/0/embed?src=c_5cd698df6784e385b1cdcdc1dbca18c061faa96959a04781566d304dc9ec7319@group.calendar.google.com>

[dune wiki on GitHub] <https://github.com/ocaml/dune/wiki>

New release of Monolith (20250314)
══════════════════════════════════

Archive:
<https://discuss.ocaml.org/t/ann-new-release-of-monolith-20250314/16303/1>

François Pottier announced
──────────────────────────

I am pleased to announce a new "Pi Day" release of Monolith.

Monolith is an OCaml library that helps perform black-box testing of
OCaml libraries, either via purely random testing, or via grey-box
fuzzing.

This new release adds new command-line options to the executable
program that Monolith produces by default. Furthermore, it extends
Monolith's API with a new function, `run', so the user can invoke
Monolith's engine as part of their own application, without letting
Monolith parse the command line. These improvements make it easier to
use a Monolith-based test as part of a continuous integration (CI)
system. Thanks to Gabriel Scherer for suggesting these improvements.

┌────
│ opam update
│ opam install monolith.20250314
└────

Happy testing!

dream_middleware_ext v0.1.0
═══════════════════════════

Archive:
<https://discuss.ocaml.org/t/ann-dream-middleware-ext-v0-1-0/16306/1>

Geoffrey Borough announced
──────────────────────────

A collection of middleware utilities for Dream framework, Initial
release v0.1.0

Currently supporting the following functionalities:

CORS: Cross-Origin Resource Sharing

Delay: simulates delayed request

Rate Limiter: supports Fixed Window and Token Bucket algorithms

Traffic Filter: supports IP, header and cookie based traffic filters

• Project page: <https://github.com/axons-talent/dream_middleware_ext>
• Documentation:
<https://axons-talent.github.io/dream_middleware_ext/dream_middleware_ext>

Learn Programming with OCaml (new book)
═══════════════════════════════════════

Archive:
<https://discuss.ocaml.org/t/learn-programming-with-ocaml-new-book/16111/13>

Continuing this thread, Jean Christophe Filliatre announced
───────────────────────────────────────────────────────────

[A preliminary EPUB version of the book] is now available. Feedback is
most welcome (preferably by [submitting an issue here]).

Big thanks to @Chet_Murthy who spent weeks working this out from our
LaTeX sources.

[A preliminary EPUB version of the book]
<https://usr.lmf.cnrs.fr/lpo/lpo.epub>

[submitting an issue here]
<https://github.com/backtracking/learn-programming-with-ocaml/issues>

Other OCaml News
════════════════

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

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

• [OCaml’s Standard Library (`Stdlib')]
• [neocaml: a new Emacs package for OCaml programming]
• [We're Moving Ocsigen from Lwt to Eio!]
• [Finding Signal in the Noise with In Young Cho]

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

[OCaml’s Standard Library (`Stdlib')]
<https://batsov.com/articles/2025/03/14/ocaml-s-standard-library/>

[neocaml: a new Emacs package for OCaml programming]
<https://batsov.com/articles/2025/03/14/neocaml-a-new-emacs-package-for-ocaml-programming/>

[We're Moving Ocsigen from Lwt to Eio!]
<https://tarides.com/blog/2025-03-13-we-re-moving-ocsigen-from-lwt-to-eio>

[Finding Signal in the Noise with In Young Cho]
<https://signals-threads.simplecast.com/episodes/finding-signal-in-the-noise-with-in-young-cho-qBmfD9v_>

Old CWN
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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
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[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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