OCaml Planet

Privacy-respecting PIM tool: host your own contacts and calendars in a secure way

2026-08-08T00:00:00-00:00

OCaml Weekly News, 04 Aug 2026

2026-08-04T12:00:00-00:00

Notes from week 31

2026-08-03T09:00:00-00:00

A big week, with a couple of long-running efforts finally wrapping up: the Source Cooperative mirror is essentially complete now that we have direct write access, and the three-week Ceph resize has converged. Elsewhere, a slow-down in the genesis job server that looked like a garbage-collector problem turned out to be an HTTP handling bug.

.plan-26-31: Sorting out Tessera and Evidence TAP infrastructure

2026-08-02T00:00:00-00:00

A petabyte of TESSERA embeddings moves to Source Cooperative, and Taposaur's GROBID metadata index and capability-based downloader take shape for Evidence TAP, while Eio gets some native Windows support.

µTCP: a TCP/IP implementation derived from a formal specification

2026-08-01T00:00:00-00:00

io_uring is not available (ENOMEM)

2026-07-29T06:00:00-00:00

Thomas reported that ocaml-multicore/eio PRs randomly fail on ocurrent/ocaml-ci with a strange error in the documentation tests.

OCaml Weekly News, 28 Jul 2026

2026-07-28T12:00:00-00:00

Autoscaling MirageOS unikernels in Mollymawk

2026-07-28T00:00:00-00:00

Notes from week 30

2026-07-27T09:00:00-00:00

The main threads: making day10 a native OCluster job type, porting opam-health-check to use day10, keeping the CI dashboards ahead of both a scraper farm and the opam 2.6 alpha, and a lot of Tessera. New v2 “student” models, the v1.1 mirror to Source Cooperative continues, and diagonal banding in the Amazon mosaic.

.plan-26-30: Bananas ripen, models open, and OxCaml releases

2026-07-26T00:00:00-00:00

An OpenUK openness interview, prototyping the Evidence TAP site with exe.dev, Windows eio support finds a user in Forester, and a new grant for optimising ranger patrols.

Reusing Buffers in Multicore OCaml

2026-07-24T00:00:00-00:00

OCaml is a pragmatic functional language: type-level tricks for safe code, careful buffer allocation for fast code. A scratch buffer in ocaml-wire raced under OCaml 5 domains; memtrace and ThreadSanitizer show both sides.

Cascade: A Typed CSS Toolkit in OCaml

2026-07-22T00:00:00-00:00

Porting Tailwind to OCaml needed a CSS parser. The parser grew a typed AST, and a structural diff and a minifier fell out of it. Cascade 1.0.0 is that toolkit, and it turns out to be competitive with the minifiers people actually use.

OCaml Weekly News, 21 Jul 2026

2026-07-21T12:00:00-00:00

Teaching Booleans About Versions: A Theory-Augmented BDD Library in OCaml

2026-07-21T12:00:00-00:00

A tour of Theo, an OCaml BDD library with complement edges for O(1) negation, ephemeron-based caching, and theory support for reasoning about version constraints and equality, turning logical equivalence into a pointer comparison.

The little type that could too much

2026-07-20T17:51:16-00:00

originally published at https://raphael-proust.github.io/code/the-little-type-that-could-too-much.html

Notes from week 29

2026-07-20T09:00:00-00:00

I was on holiday for most of week 29, so just a few high-priority issues to report on.

.plan-26-29: Perfect weather, imperfectly measured, precisely predicted

2026-07-19T00:00:00-00:00

My first viva in Law, a TESSERA stall at the House of Lords, downscaling the weather with embeddings, moving terabytes onto Source Cooperative, the Pembroke garden party, and a from-scratch shell makes progress.

Presenting styled-ppx 1.0 with CSS static extraction for OCaml

2026-07-15T17:04:51-00:00

styled-ppx is a ppx and a library that brings styled components to Melange and OCaml/Reason with type-safe CSS and static extraction. Previously styled-ppx relied on emotion.sh, and from now on, it does not. styled-ppx documentation: https://styled-ppx.vercel.app github repo: https://github.com/davesnx/styled-ppx Remote conf talk releasing styled-ppx (6 years ago!): https://www.youtube.com/watch?v=ekHCBZiCviM GambiConf: How to mimic a JavaScript feature and over-engineering CSS https://www.youtube.com/watch?v=uc5K7Yx0GvQ

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Exploring Static Data Race Freedom in OxCaml

2026-07-15T00:00:00-00:00

Discover the data-race-freedom modes of OxCaml, and how we tested them on a multicore branch of OCaml's editor service Merlin!

OCaml Weekly News, 14 Jul 2026

2026-07-14T12:00:00-00:00

Notes from week 28

2026-07-13T12:00:00-00:00

Headline activities have included resolving the scraping attacks, fixing obuilder bugs, and Tessera AMX optimisations.

.plan-26-28: What fun papers piled up while I was out at sea

2026-07-12T00:00:00-00:00

Back from the Arctic into a heatwave, hacking on Eio for the TESSERA sync engine, the Conservation Evidence team demoing at Parliament, and TESSERA on stage at the RAISE Summit in Paris.

OCaml Weekly News, 07 Jul 2026

2026-07-07T12:00:00-00:00

Notes from week 27

2026-07-05T18:00:00-00:00

The week 26 summary worked well, so I’m doing it again. This is really a nine-day week as the last weekly post was on 26 June.

Zostera: WireGuard as a MirageOS unikernel

2026-07-01T00:00:00-00:00

Why Ocsigen decided not to switch from Lwt to Eio (for now)

2026-07-01T00:00:00-00:00

Corrupt copies on the OpenBSD CI worker

2026-06-30T21:00:00-00:00

Last week I updated the OpenBSD workers to OCaml 5.5.0 and took that opportunity to deploy OpenBSD 7.8. Shortly after, issue#1061 was opened as jobs randomly failed with an opam parse error.

OCaml Weekly News, 30 Jun 2026

2026-06-30T12:00:00-00:00

.plan-26-26: Gelato, geospatial, and players of games

2026-06-28T00:00:00-00:00

Spoke at CHIA's annual conference on AI for a changing world, as well as the first Cloud-Native Geospatial Forum outside the US, and started moving TESSERA's embeddings onto Source Cooperative.

Notes from week 26

2026-06-26T18:00:00-00:00

While I typically write posts as I go, I’ve only managed one this week because there’s been a lot going on. To catch up, I’m going to try to write a summary of the week instead.

FreeBSD git-daemon leak

2026-06-24T13:00:00-00:00

The FreeBSD CI workers get slower over time. Is this a build-up on ZFS snapshots or something else?

Neocaml 0.9: A Better REPL, Dune/Opam Completion, and More Robustness

2026-06-24T07:00:00-00:00

It’s been a couple of months since the last neocaml release, and the reason is simple — for a while there I was genuinely out of ideas. Back when I shipped 0.6 I declared (again!) that I was done with new features, and this time I almost meant it. But ideas have a way of creeping back in, and 0.9 turned out to be a meaty release. Here are the highlights.

OCaml Weekly News, 23 Jun 2026

2026-06-23T12:00:00-00:00

OCaml 5.5 Summary: What's New in the Latest OCaml Update

2026-06-23T00:00:00-00:00

What's new in OCaml's latest 5.5 update? New features, performance improvements, and bug fixes.

Ocsipersist 2.1.0: type-safe persistence with Deriving

2026-06-23T00:00:00-00:00

Weeknotes 2026 week 24-25

2026-06-22T00:00:00-00:00

.plan-26-25: Planetary scale plans, Windows file-descriptor scale problems

2026-06-21T00:00:00-00:00

Ten years of the CCI with Sir David Attenborough, Andrew's Royal Society Environment Medal lecture, and the third PROPL at PLDI, while wrapping a local DeepSeek agent in OCaml and a first stab at getting Eio fleshed out on Windows.

Ocsigen in 2026: what we're working on

2026-06-19T00:00:00-00:00

A proof-of-work puzzle

2026-06-18T21:00:00-00:00

This post explores two more sustainable solutions to the crawler bots issue affecting opam-repo-ci

Grafana for MirageOS unikernels and other VMs

2026-06-18T00:00:00-00:00

Scraping opam-repo-ci to a standstill

2026-06-16T21:00:00-00:00

Jan reported that opam-repo-ci, opam.ci.ocaml.org, had become unresponsive.

Docker 29 manifest list

2026-06-16T18:00:00-00:00

On the base image builder, we have recently seen a significant increase in the number of times we hit the Docker rate limits on manifest pushes. Most of these work on the second attempt, but this week, a new class of permanent manifest push failures has emerged.

OCaml Weekly News, 16 Jun 2026

2026-06-16T12:00:00-00:00

Using OxCaml to implement type-safe reference counting between OCaml and Python

2026-06-15T00:00:00-00:00

Jane Street is known for being an OCaml shop, but for years now Python has been our second major programming language, acting as the primary tool for data an...

Language integrated LLMs as an OCaml function

2026-06-14T00:00:00-00:00

Using a local DeepSeek model as an ordinary OCaml library and building sandboxed agents from simple primitives

.plan-26-24: Apparently a professor now; still debugging io_uring at midnight

2026-06-14T00:00:00-00:00

Made professor at Cambridge, shipped TESSERA v1.1, bound a local DeepSeek into OCaml after Fable cut out, and filled the gaps in io_uring and Eio.

A new home for the Ocsigen blog

2026-06-14T00:00:00-00:00

Tessera v1.1 released, with smoother and temporally stable embeddings

2026-06-12T00:00:00-00:00

TESSERA v1.1 is a drop-in retrained model that fixes the tiling artefacts of v1.0, with embeddings now being served from AWS S3 and model weights up on Hugging Face.

Removing HCS containers

2026-06-10T20:00:00-00:00

The Windows workers in the windows-x86_64 pool have a habit of quietly falling off the cluster. The ocluster-worker service is still RUNNING, but the scheduler lists the worker as disconnected.

ocgtk development update: June 2026

2026-06-10T00:00:00-00:00

Development update for ocgtk (a set of GTK4 bindings for OCaml), including upcoming support for signals and interfaces, expanded GLib type coverage, and packaging improvements to support other operating systems.

OCaml Weekly News, 09 Jun 2026

2026-06-09T12:00:00-00:00

Week 23, June 2026

2026-06-08T00:00:00-00:00

.plan-26-23: Earth Embeddings, Emails Everywhere, and ERRNOOOs

2026-06-07T00:00:00-00:00

TESSERA on the ESA homepage and at CVPR, GeoTessera 0.9 stabilising onto S3/Zarr, io-uring in OCaml, carbon credits in New Scientist and WSJ, and musings on internet malware again.

Documenting OCaml projects with wodoc

2026-06-07T00:00:00-00:00

Docker 29 and COPY –link –chown

2026-06-06T22:00:00-00:00

After deploying the QEMU RISC-V machines, the base image builder ran into issues on the first Docker build.

Self-hosting email the hard way from your own routable IPv4 block up

2026-06-06T00:00:00-00:00

How we refreshed self-hosted Recoil email with our own RIPE-allocated IPv4 block, and deployed Postfix/rspamd/Dovecot to get full SPF/DKIM/DMARC deliverability.

Emulating RISC-V workers when the hardware goes away

2026-06-03T18:00:00-00:00

Scaleway provide the RISC-V workers for OCaml CI, and they have been down for about a week with no real evidence that they’ll be back anytime soon. I can’t provision any new ones as they are “temporarily out of stock”.

OCaml CI lingering solves

2026-06-02T20:00:00-00:00

By now, you’ll know that I’ve been looking at OCaml CI more than I ever had before and was confused by the solver jobs, which seemed to hang around in the job queue.

OCaml CI GitHub Rate Limit

2026-06-02T14:00:00-00:00

While looking at OCaml CI for the FD leak, I noticed some odd pending events in the OCaml CI build graph.

OCaml Weekly News, 02 Jun 2026

2026-06-02T12:00:00-00:00

Dynamic Logging and Metrics with Mollymawk

2026-05-31T00:00:00-00:00

.plan-26-22: From digital rewilding in Edinburgh to uring and Tessera hackery

2026-05-31T00:00:00-00:00

Rewilding the Web workshop in Edinburgh, an OCaml io_uring binding refresh, and GeoTessera 0.9 moves the embeddings to AWS alongside a fresh HuggingFace org.

Rewilding the Web: my workshop report from Edinburgh

2026-05-30T00:00:00-00:00

Notes from a wonderfully interdisciplinary Edinburgh workshop on 'Rewilding the Web', ranging coopetition and biological variety through the philosophy of self-organisation, polycrisis governance, protopian science fiction, and moderation seen through the lens of artisanal cheese.

OCaml-CI HTTP 502 errors

2026-05-28T14:00:00-00:00

Over the last few weeks, I have restarted the OCaml-CI web container every 3 or 4 days because users are encountering HTTP 502 errors.

OCaml Weekly News, 26 May 2026

2026-05-26T12:00:00-00:00

.plan-26-21: Pint of Science, OxCaml dissertations, and TESSERA 1.1 stirring

2026-05-24T00:00:00-00:00

After the BBC/ITV media run we had a talk at Pint of Science, two cracking Part II dissertations on CE/TESSERA and OxCaml vector RAG, and put TESSERA v1.1 weights on HuggingFace.

UI/UX improvements in Mollymawk

2026-05-20T00:00:00-00:00

OCaml Weekly News, 19 May 2026

2026-05-19T12:00:00-00:00

.plan-26-20: Putting OxCaml in a box and OCaml in orbit (again)

2026-05-17T00:00:00-00:00

Consolidating my OCaml trees for easier OxCaml deployment, shipping native system packages for OxCaml which then got into space, and remembering Peter Neumann

Building OxCaml packages for Debian, Fedora, Homebrew and Arch

2026-05-17T00:00:00-00:00

Native OxCaml system packages for Debian/Ubuntu, Fedora, Arch and Homebrew — plus reviving a 2013 GPG key that modern tooling rejects for SHA-1, and using agentic coding to collapse the opam build into one tarball.

Voluntary AI disclosure proposal for OCaml: update 1

2026-05-14T00:00:00-00:00

An update on the voluntary AI disclosure proposal, digesting the security, quality and legal feedback, and some concrete next steps around maintenance intent, multi-repository tooling, and reputation.

O(x)Caml in Space

2026-05-14T00:00:00-00:00

On 23 April, Borealis booted in orbit on DPhi Space's ClusterGate-2: a pure-OCaml CCSDS protocol stack with end-to-end-encrypted command and control and post-quantum key rotation. OxCaml is what comes next.

Emulating inheritance without classes

2026-05-13T00:00:00-00:00

The O in OCaml is for its object-oriented extension, but I needed a way to emulate the constraints of inheritance without it. This raised some interesting design questions about how to do it using only the core ML language.

Odd opam update behaviour

2026-05-12T18:00:00-00:00

A few days after retiring opam 2.0 from the build pipeline, ocaml-ci Jon noticed that some jobs were failing. I immediately concluded that the removal was to blame, but it wasn’t.

OCaml Weekly News, 12 May 2026

2026-05-12T12:00:00-00:00

What is Functional Programming? A Look at the Programming Style from an OCaml Perspective

2026-05-12T00:00:00-00:00

Get a comprehensive overview of the definitions, benefits, trade-offs, and use cases of functional programming.