The OCaml Planet RSS

We've all seen satellites drifting by at night, and wondered how many are actually up there. With how long they have been observing Earth, it is unsurprising that satellites have accumulated a vast library of images covering the globe. In a world increasingly focused on identifying and mitigating human impact on the natural world, these images constitute an untapped data resource. Sadly, most conservation groups, field biologists, and local policymakers don't have a supercomputer on stand-by to help them trawl through that data and analyse trends. This is where the AI model Tessera, co-funded by Tarides and developed by a team headed by the University of Cambridge, comes in. What is Tessera? Tessera is an open-source AI foundation model which can parse through petabytes of satellite data to reveal patterns and changes over time. Tessera lets scientists designate habitat maps and highlight the changes they want to monitor over time. It can be used to reveal environmental changes, such as crop patterns, habitat loss, and deforestation. The software processes millions of satellite images from the European Space Agency into a compact, easily usable format for scientists. The result is that, instead of needing a supercomputer, researchers have access to global-scale analyses from their laptops. Tessera's algorithm learns to understand the 'fingerprint' of a landscape, knowing what it should look like, which allows it to fill in cloud-covered images with the missing values. For each 10-by-10-metre of land on Earth, the software creates an uninterpreted sequence of 128 numbers called 'embeddings'. All of these embeddings are available on demand in the database GeoTessera. A recent example comes from the Scottish Highlands, where a Cambridge-led team used aerial surveys to build detailed 3D maps showing the beginnings of large-scale native woodland recovery across the Cairngorms National Park. Tarides supported that work, and the data feeds into Tessera. You can read the University of Cambridge write-up. To learn more about the project, you can read the article published by the University of Cambridge, the open access paper, and watch the webinar on Tessera. Tessera & Tarides: A Natural Fit with our Work in Space We are proud to have sponsored Tessera's development, since it is open source and has no paywalls by design. As Tessera's co-lead, Anil Madhavapeddy, professor of planetary computing at Cambridge, puts it: the goal is to "democratise satellite data for people who lack massive computer resources, whether that's an underfunded conservation group here in the UK, field biodiversity researchers in the majority world, or planners figuring out climate adaptation strategies in a rapidly warming world." Tarides is dedicated to building secure and sustainable software with a positive impact, and supporting the Tessera project is a natural fit. It also complements our work on satellite software. Our sister company, Parsimoni, has been putting OCaml and MirageOS into orbit through SpaceOS, and we've built Notafs, a filesystem that lets Irmin run on MirageOS unikernels aboard satellites. Earlier this year, we also kicked off our part in the CEOS project, building next-generation Earth observation satellites. Tessera is a piece of that same puzzle; it's one thing to get reliable, secure software into orbit and collect data, and another to make sense of what that data is telling us once it's back on the ground. Whether it's the satellite hardware and unikernels collecting the imagery, or a foundation model turning that imagery into insight for a conservation group with no cloud budget, the focus for us is the same: open tools should make space and Earth science more accessible, not less. What's Next & Stay in Touch Explore Tessera's embeddings yourself at geotessera.org, and share your thoughts with the team behind the model. Stay in touch with us on Bluesky, Mastodon, and LinkedIn or sign up to our mailing list to stay updated on our latest projects. We look forward to hearing from you!

uniker.nl - Unikernels in OCamlAnnouncing segmap, a fast data structure for renamingshexen.0.1intel_hex.1.0Js_of_ocaml / Wasm_of_ocaml 6.5TIFF Inspector: an ocaml-tiff based inspector, with an in-browser OCaml playgroundOCaml 5.5.2 releasedbytream.0.4First release of spvecocaml-emcc: compile OCaml programs with their C stubs to WebAssemblyNew release of snkv-ocaml 0.3.0 — OCaml bindings for SNKV with HNSW vector searchBuilding TIFF Inspector: Exploring OCaml, TIFF Internals, and an In-Browser Playgroundstele 0.1.0: syntax-error messages for Menhir grammarsOSEC-2026-21: Str partial-match stale capture registers underflowOSEC-2026-22: Integer overflow in Unix.map_fileOSEC-2026-23: Multiple issues in MarshalOSEC-2026-24: Multiple issues in command quoting on WindowsOSEC-2026-25: Heap buffer overflow in the OCaml ~runtime_events~ consumer when parsing an oversized custom user eventOSEC-2026-26: runtime_events user event name-based type confusion

ocaml.org memory and CPU improvements; the first Tessera block processed straight into the Zarr store; a CephFS kernel bug that returned zeros for files that were fine; and day10 updates.

I have always been a fan of asciinema and of Charm's VHS. asciinema records a terminal while you use it, and VHS types a script of commands into a terminal and films the result. I wanted their animations in the READMEs of my projects, but I always forgot the syntax of VHS's tape files, and I always mistyped a command halfway through an asciinema recording (and then started again). I also always forgot to re-run those recordings when my API changed, and they got out of sync quickly. Fortunately, most of my projects already check their command-line output with cram tests, transcripts of shell commands and of what they print, which dune, OCaml's build system, runs as tests. Making those tests produce animated images was a short stretch, and then, why stop there? The result is k7 (how the French write cassette, if you say it out loud), a command-line tool that records any program, whatever its language, as an SVG image animated with CSS alone. Here is ls, and sl, which I regularly enjoy mistyping. Each took one command, such as k7 rec -o sl.svg -- sl, which generates an animation you can embed in any HTML page (and in your projects' READMEs). ls, as I meant to type it. sl, as I actually typed it. Animations that dune checks I was not the first to draw a terminal as an animated SVG. termtosvg (now archived) and svg-term-cli do it too. What k7 adds, I think, is that it both writes and plays dune's cram tests. A cram test is a text file that reads like a terminal session. Each command is indented and starts with $ , the output it should print sits below it, and any other line is a comment: Print a greeting: $ printf 'hello\n' hello dune test runs the commands of each test in a new empty directory and compares what they print with the file. When the output changes, dune shows the difference, and dune promote writes the new output into the file. k7 fits into that loop at both ends. k7 rec -o hello.t -- printf 'hello\n' writes the test above (without the comment). In the other direction, k7 play types the commands of a cram test into bash and draws what happens. The image at the top of k7's README comes from doc/demo.t, drawn by k7 play -o doc/demo.svg doc/demo.t. Dune runs the same file as a test, so the test fails exactly when the image needs drawing again, and drawing it again takes one command. doc/demo.t from k7's repository, typed into bash by k7 play. The same screen as VHS, every time k7 rec runs a program on a pseudo-terminal and feeds what it prints to a terminal emulator, matrix, from Thibaut Mattio's mosaic project at Invariant Systems. I wanted k7 to draw the same screens as VHS, which runs xterm.js in a browser, so I fixed the places where matrix and xterm.js disagreed and sent the fixes upstream. Each time the program changes the screen, k7 keeps a copy of it, at most 50 times a second (as in VHS). Each distinct line of text is defined once, each frame refers to the lines it shows, and a single CSS @keyframes rule slides the strip of frames, jumping to each one at the time the program drew it. This keeps the file small when most lines stay put: the image of ls above takes 4 KB. A train crossing the screen is the worst case, and the image of sl takes 356 KB. The GIF that VHS made of the same sl, on a terminal of the same size, takes 2.1 MB. VHS drives a headless browser and encodes the frames with ffmpeg, and on my laptop it took 53 seconds, against 8 for k7 rec, about 7 of which were sl itself. A program like sl has no cram test, since its output is an animation rather than text. For those, k7 rec -o sl.cast -- sl keeps the recording itself, in asciinema's asciicast v3 format, and k7 play draws it, or any asciinema recording, without running anything. Recording is not deterministic, but drawing is. Record sl twice and the two recordings differ, because the program never prints at quite the same times. Draw one recording twice and you get the same file, byte for byte. So dune can check a committed image against the recording beside it: (rule (target sl.generated.svg) (action (run k7 play -o %{target} %{dep:sl.cast}))) (rule (alias runtest) (action (diff sl.svg sl.generated.svg))) A tape syntax the compiler remembers That leaves the VHS tape syntax I kept forgetting. k7 plays .tape files too, and in OCaml, the K7 library builds tapes as values instead, so the compiler remembers the syntax for me: let tape = K7.tape ~settings:K7.[ Font_size 18; Width 1000; Height 560 ] ~outputs:[ "demo.gif" ] K7.[ type' "dune test\n"; wait Prompt; sleep (Ms 2000) ] K7.tape checks the tape against the rules of VHS's parser as soon as it is built, theme name included, where VHS only notices a misspelt theme when it runs the tape. Its tests hold it to vhs validate on 3000 random tape lines, as I held my Tailwind rewrite to Tailwind itself. Trying it k7 0.9.0 is in my Homebrew tap, for macOS and Linux, and on opam for OCaml 5.4 and later: $ brew install samoht/tap/k7 $ opam install k7 A few edge cases are not supported (the README lists them), but for most uses it seems to work fine. If k7 draws something differently from VHS or asciinema, please open an issue with the recording (k7 rec -o bug.cast -- yourprogram makes one).

Forester toplevels are working well in FoCS lectures, a smooth Patch the Planet week with Trail of Bits, and drowning in security reports.

opentelemetry 0.92

A new workflow to develop and deploy unikernels

day10 reverse dependencies are live and found a dune regression; the aardvark 2017 run finished; and the v2~beta1 Zarr store was rebuilt on a grid that no longer depends on its own data.