OCaml Weekly News

AFAIK this is implemented in OCaml:

https://medium.com/darklang/how-dark-deploys-code-in-50ms-771c6dd60671

We are pleased to announce the minor release of opam 2.0.5.

This new version contains mainly build updates & lint fixes. You can find more information in this blog post.

There is already a very good fork of opam for Windows here. My work has been on changes to upstream opam to improve the native experience. The 2.0 branch of opam builds on Windows, but the resulting binaries are not terribly useful (you can't get past opam init). The master branch of opam now contains sufficient support to pass the testsuite (I haven't yet ported the regression testing framework, although I don't see why that fundamentally shouldn't be passing too). At present I'm making a final push to complete the shell integration parts of opam init and opam env, at which point we can upgrade the ocaml-base-compiler packages in opam-repository with Windows build instructions.

After that, there's a quartet of features which benefit opam in general, but are specifically useful for Windows:

• a replacement of base packages with base constraints, which is in progress in #3894. This actually provides a much more elegant solution to system compiler upgrades; for Windows, it's original was that it permits upgrading and pinning FlexDLL, which is a C dependency of the Windows ports of OCaml.
• the introduction of a new predicate to limit automatic selection of packages by the solver, which will mean, amongst other things, that opam install ocaml will never select a variant or trunk compiler (not started yet, although the semantics of it are more complicated than the implementation). For Windows, it will mean that the switch will not randomly try to change the C compiler the switch is based on (i.e. switch Windows port).
• build environments, which generalise the present "system" build environment. For Unix (well, and Windows 10), this would include having a Docker container associated with a switch and, for Windows, would also permit using separate Cygwin/MSYS and eventually WSL installations for package building. In general, it would also permit switches to have different depexts installed, since you'd no longer have to be tied to what's installed on your actual system (that's not started yet, either)

• package parameters. There have been various proposals on this before (including the one referenced above, which is actually superseded by the new predicate). I have a (new) prototype implementation which allows specifying things like flambda (and so, for Windows, some of the port selection information) as part of opam install, opam reinstall or opam switch create. There's a bit of tightrope to walk with this one, as changes here need to remain compatible with an opam 2.0 mainline repository.

It's not clear exactly what's going to land in opam 2.1, which is trying to head towards beta soon and 2.2 which should be relatively hot on its tail later in the year. I would add that reimplementing tools in OCaml, while a highly worthy endeavour, merely transforms the nature of the shell problem!

MacPorts has been updated to the new version of opam as of a few moments ago; it may take a couple of hours for mirrors to synchronize.

Same with homebrew, it was merged 20h ago and binaries should be built sometime.

Dear OCaml hackers and enthusiasts,

the fourth edition of the OCaml MOOC will start in September. Please, take a minute to spread the word around you!

Three possible actions:

1. Convince everyone you know to register at https://tinyurl.com/ocamooc4
2. Print, post and share our flyer https://bit.ly/2YrSVLF
3. Post the announcement message which is pasted at the end of this email.

By the way, we would like to thank the sponsors of the OCaml Software Foundation for their support. Without it, the OCaml MOOC would not exist.

Thank you all for your help!

Roberto Di Cosmo, Yann Régis-Gianas and Ralf Treinen.

As we are preparing the Dune 2.0.0 release, we wanted to share a few words about it. Most of it is straightforward. One notable change is that Dune 2 will require a recent version of OCaml to build itself, however it will still be able to build projects using older compilers and will still be installable in older opam switches. We will also provide one additional year of support for Dune 1.

https://dune.build/blog/dune-2-coming-soon/

It is my pleasure to invite participation in the OCaml Users and Developers Workshop 2019, which is again co-located with ICFP and will be held on Friday 23rd August, 2019 in Berlin, Germany.

http://ocaml.org/meetings/ocaml/2019/

Early bird registration deadline: July 18th, 2019

The OCaml Users and Developers Workshop brings together the OCaml community, including users of OCaml in industry, academia, hobbyists and the free software community. Previous editions have been co-located with ICFP since 2012 in Copenhagen, Boston, Gothenburg, Nara, Oxford and last year in St Louis, following OCaml Meetings in Paris in 2010 and 2011.

https://icfp19.sigplan.org/home/ocaml-2019

Registration for the workshop day is required, but not for the entire conference. There are several talks with an OCaml flavour in the ML Workshop, which is the previous day (August 22nd). Note that although the precise talk schedule is not yet finalised (it should be by the end of this week), once registered for the day, it is possible to move between workshops.

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

• OCaml Developer at Ahrefs Pte Ltd (Full-time)
• opam 2.0.5 release
• opam 2.0.5 release
• The Alt-Ergo SMT Solver’s results in the SMT-COMP 2019
• Of Pythons and Camels