OCaml Weekly News

We are very pleased to announce the immediate availability of the latest stable release of Learn-OCaml, version 0.13.0.

Many thanks to all users and developers that reported bugs, contributed features or patches ✨ and in particular, special thanks go to @yurug and @AltGr for their precious advice and help during the preparation of this release.

A (mostly) comprehensive list of the features, fixes, and enhancements offered by this release is available in the Release Notes.

Beyond this list of changes, note that:

• We now switch to semantic versioning, so that this version is git-tagged v0.13.0 and not just 0.13.
• The REST API did not change (between the previous stable version 0.12 and version 0.13.0).
• The "exodir" format has been slightly extended (but the documentation online of these changes is not yet up-to-date), keeping a strong focus on backward-compatibility (see e.g. PR #397 for related remarks).
• All the main binaries of Learn-OCaml (learn-ocaml-client, learn-ocaml, and the native learn-ocaml-server) are now statically built and available in the Release page, for Linux and macOS.
• The whole codebase of Learn-OCaml has been ported to OCaml 4.12 (including the toplevel environment that is exposed to students).
• We now relax the coupling between client/server, and commit to keeping backward-compatibility for the latest learn-ocaml-client w.r.t. the previous versions (so, learn-ocaml-client.0.13.0 can interact with servers learn-ocaml.{0.12, 0.13.0} smoothly − see PR #426 for context).
• The learn-ocaml-client CLI API did not change, except that a command learn-ocaml-client server-version has been added, to distinguish between the server version and the (possibly more recent) learn-ocaml-client --version (see PR #429 for details).

• Docker images are still available on Docker Hub, e.g., to easily spin a local server from a repository exercises, you can do:

  sudo docker run --name=server-test -v "$PWD/demo-repository:/repository:ro" \
    -p 8080:8080 ocamlsf/learn-ocaml:0.13.0
  

  More details on the Docker setup can be found in How to deploy a learn-ocaml instance.

• (If you migrate from 0.12 to 0.13.0 in your deployments, beware that the mere bump of OCaml's version may cause some of your graders to fail.)
• A dedicated PR has also been opened in opam-repository.
• As noted above, several architectural changes have been done about the learn-ocaml-client as this tool plays a

key "pivot" role, for students that would like to use Tuareg+Merlin+learn-ocaml-mode and interact with a Learn-OCaml server backend directly from Emacs (and thus benefit from the advantages of both Merlin and Learn-OCaml's exercise grading feature).

We hope to be able to release 0.14.0 soon, specifically to integrate the pending PR #372 that will solve a long-running issue with auto-Sync and students-code overwriting; and we also plan to extend learn-ocaml's backend and REST API soon to further enhance the UX of learn-ocaml.el, at least to lift this limitation (for which we have a working proof-of-concept to be refined).

If need be, feel free to open issues in the Learn-OCaml bug tracker (GH) or post in this thread to share thoughts or experience-feedback.

Hot on the heels of the OCaml 4.13 announcement(s!), the odoc team is pleased to announce the release of odoc 2.0.0!

tl;dr: The new version produces much better output than the old version, it's the engine at the core of the package docs in v3.ocaml.org, and it also has a new website.

This release has been a long time coming – years! – and contains several notable improvements over the odoc 1.5 series: a new language model, a new rendering layer allowing output in several formats, and improved control over the output structure.

With the convergence between the multicore and standard runtime across OCaml 4.10.0 to 4.13.0, the development of OCaml multicore has reached a point where further integration into OCaml's main branch requires fully committing to a switch to OCaml multicore.

The OCaml team has decided that the time has come for such a commitment. The new major version, OCaml 5, will be a multicore version of OCaml. Moreover, OCaml 4.14 will be the last minor release of the 4.x series of OCaml.

I've also submitted a project for the winter session: "Create a tool to show differences in the output of odoc."

The idea is to produce a tool to work on the output of the ocaml-docs-ci pipeline to find differences between different versions of the same package. We're aiming for it to eventually be used in the docs pages to highlight differences between versions in v3.ocaml.org. Just one of the neat things we've got in mind for the docs pages on the new website!

As @tmattio points out, you don't have to be a mentor to contribute to the process - so let the odoc team know if you're interested in lending a hand.

0.2.2 is now released.

Some of the bigger changes:

• (Bug Fixes) Many problems with Visual Studio have been resolved, especially for non-English installations.
• (Features) Pre-alpha support for macOS and Windows 32-bit, in addition to the existing Windows 64-bit support.
• (Reliability) There is now an internal GitHub Actions CI system that builds Windows 32-bit, Windows 64-bit and macOS (x64). In the future GitHub Actions will be offered to anyone who needs to test their own 32-bit and 64-bit Windows packages.
• (Reliability) The Windows MinGW Opam repository vended by fdopen is still used but has been drastically pruned. Now the thousands of MinGW and DKML (MSVC) patches are pinned, and those pinned package versions are tested with the GitHub Actions CI system.

To upgrade, just follow the Two Step installation instructions and then upgrade any of your Local Projects like diskuv-ocaml-starter with ./makeit build-dev .

The v0.2.2 release notes has a detailed list of changes.

I'm pleased to announce the first release of osh, a website providing an API to generate SVG badges.

E.g. this url: https://osh.ocamlpro.com/badge?label=build&color=green&status=passing will give the following result: build passing.

We also have special support for GitHub actions, using https://osh.ocamlpro.com/badge/github/workflow/status/OCamlPro/swhid/build.yml will give you the following: build passing.

Even when using the special GitHub action endpoint, you can override any parameter, e.g. https://osh.ocamlpro.com/badge/github/workflow/status/OCamlPro/swhid/build.yml?color=blue will give you the following: build passing.

We're willing to add any other special endpoint if someone is interested. :)

The source code is available on OCamlPro's Gitlab, it's made with ocb for the badge generation part, dream, ezcurl, omd, crunch and Yojson.

There's also an opam package in case you want to host your own instance.

Enjoy !

I have the pleasure to announce the first release of pyast, a library provides versioned abstract syntax tree for all Python versions from Python 2.5 to Python 3.10.

Available on opam: opam install pyast

The purpose of this library is very close to pyre-ast, namely being able to give access from OCaml programs to the Python own parser and to the ASTs it builds. There are two main differences:

• pyre-ast exposes the AST of Python 3.10 whereas pyast exposes the ASTs of all Python versions from Python 2.5 to Python 3.10 (in versioned modules à la ocaml-migrate-parsetree), providing converters between them. The AST of the latest version of Python (currently, 3.10) is provided in Pyast.Latest.
• pyre-ast embeds its own version of the Python interpreter, whereas pyast uses the Python interpreter available on the machine (via pyml), converting the AST to the expected version if necessary.

The development of pyast was motivated when some handwritten code using pyml to access the Python parser broke after a Python upgrade because of a change in the AST!

The Software Safety and Security Lab at CEA LIST (Université Paris-Saclay, France) is opening 2 postdoc, 1 PhD, and 1 internship positions in the area of runtime verification for code safety and security:

• postdoc: Designing Compilation Techniques for Improving Efficiency of E-ACSL, a Runtime Assertion Checker for C Programs https://julien-signoles.fr/positions/postdoc-eacsl.pdf
• postdoc: Control Flow Integrity for Remote Attestation https://julien-signoles.fr/positions/postdoc-cfi.pdf
• PhD: Outline Runtime Assertion Checking (possibly preceded by an internship on the same topic if needed) https://julien-signoles.fr/positions/phd-outline-rac.pdf
• internship: C Function Synthesis from Axiomatic Definitions (in French, please ask for an English version) https://julien-signoles.fr/positions/master_axiomatics.pdf

The candidates will:

• solve challenging research problems;
• implement their results in Frama-C, an industrial-strength open-source framework for analyses of C code;
• evaluate their solutions on concrete benchmarks or/and use cases;
• publish their results in international conferences and journals.

Strong knowledge in at least one of the following areas is always appreciated:

• programming: OCaml and C, semantics of programming languages, …
• formal verification: runtime verification, static analysis, …
• compilation: code generation, program transformation, type system, …

Interested applicants should send a CV and a motivation letter to Julien Signoles (julien dot signoles at cea dot fr) as soon as possible.

We have an opening for a post-doctoral research position at The University of Edinburgh on Effect Handler Oriented Programming (EHOP) funded by a UKRI Future Leaders Fellowship.

Candidates should have a background in programming languages with experience of functional programming, formal semantics, and type theory. Some experience with effect handlers and algebraic effects is desirable, but not essential. The role will involve theory (e.g. developing and reasoning about novel effect type systems and algebraic theories) and practice (e.g. designing, implementing, and evaluating implementations and applications of effect handlers), and ample opportunity to engage with our project partners (several of whom are deeply involved with the development of OCaml).

The position is for three years starting in February 2022.

The EHOP project:

https://effect-handlers.org/

Job application details:

https://elxw.fa.em3.oraclecloud.com/hcmUI/CandidateExperience/en/sites/CX_1001/job/2087/

If you are interested then feel free to contact Sam Lindley (application deadline: 1 November 2021).

I’m happy to publish the third issue of the “OCaml compiler development newsletter”. (This is by no means exhaustive: many people didn’t end up having the time to write something, and it’s fine.)

Feel free of course to comment or ask questions!

If you have been working on the OCaml compiler and want to say something, please feel free to post in this thread! If you would like me to get in touch next time I prepare a newsletter issue (some random point in the future), please let me know by email at (gabriel.scherer at gmail).

Previous issues:

• OCaml compiler development newsletter, issue 2: May 2021
• OCaml compiler development newsletter, issue 1: before May 2021

It's my pleasure to announce the release 0.0.7 of odig. Odig is a command line tool to lookup documentation of installed OCaml packages.

Once it has made it to the repo, install with opam install ocaml-manual odig and consult the manual (or via odig doc odig).

This release provides support for odoc 2.0.0. The release notes have all the details.

Note! This is not our usual time! Past meetups have been at 7pm (U.S. Central). This one is happening at 1pm (U.S. Central). This meetup should be easier for people in Europe to attend.

Please join us at the next OCaml Cafe, a friendly, low stakes opportunity to ask questions about the OCaml language and ecosystem, work through programming problems that you’re stuck on, and get feedback on your code. Especially geared toward new and intermediate users, experienced OCaml developers will be available to answer your questions. Bring your code and we’ll be happy to review it, assist with debugging, and provide recommendations for improvement.

This month, David Allsop of OCaml Labs and the University of Cambridge will present on OPAM, the OCaml package manager. After introducing OPAM, David will discuss the new features of OPAM 2.1, just released at the beginning of August. Following David's talk, we will open the discussion to all things OCaml-related.

Full meeting details, including Zoom link, here: https://www.meetup.com/ocaml-cafe/events/281344155/

The multicore eio lib has now been migrated to the syntax-free version. This is the version of effects which will be available in the upcoming OCaml 5.0.0.

PR : https://github.com/ocaml-multicore/eio/pull/82

I’m pleased to announce the release of Alcotest 1.5.0, now available on Opam.

This release includes:

• JavaScript compatibility (#326), via js_of_ocaml.3.11.0. Projects that build with js_of_ocaml can now use the regular alcotest package to test their JavaScript-compatible libraries. For users of dune, this is as easy as adding (modes ... js) to your test stanzas (to build the JavaScript targets) and a corresponding rule to run the output:

  (test
   (name main)
   (modes native js)
   (libraries alcotest))
  
  (rule
   (alias runtest-js)
   (action
    (run node %{dep:main.bc.js})))
  

  To depend on a version of js_of_ocaml that is supported by Alcotest, add a dependency on the the virtual package alcotest-js.

  Many thanks @hhugo and @smorimoto for this excellent contribution!

• Backtrace collection by default (#317). The Alcotest runner now enables backtrace collection by default, ensuring that failing native tests always come with backtraces without any need to set OCAMLRUNPARAM=b.
• A stable Alcotest.V1 module (#306). This module is very similar to the existing top-level Alcotest module, but provides some stability guarantee across major versions. It's intended to provide a migration path for an eventual "Alcotest 2" to make improvements on the existing API.

The full changelog is available here.

Here are links from many OCaml blogs aggregated at OCaml Planet.

• The New Replaying Benchmark in Irmin