OCaml Weekly News

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Here is the latest OCaml Weekly News, for the week of July 07 to 14, 2020.

Table of Contents

OCaml 4.11.0, second beta release

octachron announced

The release of OCaml 4.11.0 is approaching. As one step further in this direction, we have published a second beta release. This new release fixes an MSVC-specific runtime issue.

The compatibility of the opam ecosystem with OCaml 4.11.0 is currently quite good with only 7 packages not currently available, and it should be possible to test this beta without too much trouble.

The source code is available at these addresses:


The compiler can also be installed as an OPAM switch with one of the following commands:

opam switch create ocaml-variants.4.11.0+beta2 --repositories=default,beta=git+https://github.com/ocaml/ocaml-beta-repository.git


opam switch create ocaml-variants.4.11.0+beta2+<VARIANT> --repositories=default,beta=git+https://github.com/ocaml/ocaml-beta-repository.git

where you replace <VARIANT> with one of these: afl, flambda, fp, fp+flambda

We would love to hear about any bugs. Please report them here: https://github.com/ocaml/ocaml/issues

If you are interested by the list of new features, and the on-going list of bug fixes the updated change log for OCaml 4.11.0 is available at:


Compared to the previous beta release, the exhaustive list of changes is as follows:


  • #9714, #9724: Use the C++ alignas keyword when compiling in C++. Fixes a bug with MSVC C++ 2015/2017. Add a terminator to the caml_domain_state structure to better ensure that members are correctly spaced. (Antonin Décimo, review by David Allsopp and Xavier Leroy)

Manual and documentation

  • #8644: fix formatting comment about @raise in stdlib's mli files (Élie Brami, review by David Allsopp)
  • #9712: Update the version format to allow "". The new format is "major.minor[.patchlevel][(+|)additional-info]", for instance "4.12.0~beta1+flambda". This is a documentation-only change for the 4.11 branch, the new format will be used starting with the 4.12 branch. (Florian Angeletti, review by Damien Doligez and Xavier Leroy)

letters - simple client abstractions for sending emails over SMTP

Miko announced

Earlier today I've published the first release of letters. This library aims to provide simple to use client library for sending emails over SMTP using lwt for async execution.

It is build on top of mrmime and colombe. While these libraries are very capable, they aren't that simple to use, letters is trying to fill that gap. Anyway, big thanks for the authors of these projects for doing the heavy lifting.

As this library is still in its early stage, I believe I will break the API with first few releases. Luckily the API is quite simple so following these changes should be quite easy.

To make this library awesome, any feedback or feature request is welcome. I'll try to address them as quickly as I can.

I hope I've managed to scratch someone else's itch too, enjoy.

A question about Ocaml

Deep in this theard, Yawar Amin said

A few ReasonML books:

Alcotest 1.2.0

Craig Ferguson announced

I'm pleased to announce the release of Alcotest 1.2.0, now available on Opam.

This release includes:

  • a new alcotest-mirage package for running tests on MirageOS;
  • full UTF-8 support;
  • default coloured output in Dune (without needing to pass --no-buffer);
  • an improved output format.

The full changelog is available here.


Thanks to our many contributors in this release cycle.

Set up OCaml 1.1.0

Sora Morimoto announced

This release contains these changes:

  • The default opam repository can now be set via input.
  • Linux VMs now use opam 2.0.7.


Sora Morimoto then added

In fact, this release was a long time ago, but I completely forgot to post this. By the way, we have made significant improvements to some of the documentation. In particular, the action versioning section is applicable to other GitHub Actions and definitely worth reading! https://github.com/avsm/setup-ocaml#how-to-specify-the-version


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