ocaml-multicore VS dune

1. Domains are the unit of parallelism. A domain is essentially an OS thread with a bunch of extra runtime book-keeping data. You can use Domain.spawn (https://github.com/ocaml-multicore/ocaml-multicore/blob/5.00...) to spawn off a new domain which will run the supplied function and terminate when it finishes. This is heavyweight though, domains are expected to be long-running.

2. Domainslib is the library developed alongside multicore to aid users in exploiting parallelism. It supports nested parallelism and is pretty highly optimised (https://github.com/ocaml-multicore/domainslib/pull/29 for some graphs/numbers). The domainslib repo has some good examples: https://github.com/ocaml-multicore/domainslib/tree/master/te...

3. We've not tested against other forms of parallelism. There isn't anything stopping you exploiting SIMD in addition to parallelism from domains.

4. No, we've not compared performance by OS.

5. No plans for the multicore team to look at accelerator integration at the moment.

For Algebraic Effects and Multicore OCaml specifically, I have this intro saved and they've been publishing regular updates here's October's. They have a paper linked from their repo's README but I don't remember the contents offhand.

Until recently Multicore OCaml was focused on deep handlers. The people working on the formalization of effects (either for program proofs or typed effects) were quite keen to have shallow handler integrated however. Thus, the effect module of the OCaml 5 preview contains both (see https://github.com/ocaml-multicore/ocaml-multicore/blob/5.00...) since September. I fear that non-academic literature has not followed this change (on the academic side, see https://dl.acm.org/doi/10.1145/3434314 for a program proofs point of view).

Yes, it's announcing that the next but one version, 5.0, will support multicore and effect handlers.

For what it's worth you can actually start using Multicore OCaml today, there are installation instructions on the wiki: https://github.com/ocaml-multicore/ocaml-multicore

ocaml-multicore/ocaml-multicore

Could you explain (in simple terms if possible) how the Multicore OCaml achieves a memory model which is much simpler on more efficient than in Java or C (mentioned at https://github.com/ocaml-multicore/ocaml-multicore/wiki)?

Didn't see any mentions of critical sections (mutexes) with C++ examples in the documentation ("Bounding Data Races in Space and Time"). I'm not sure I understand the comparisons the writers are presenting.

There are getting started instructions up on https://github.com/ocaml-multicore/ocaml-multicore

If you are using the dune build system, add the tag(s) to your dune-project file's package stanza. E.g.:

One way to get around this is to modify the api/dune file with (include_subdirs qualified); this means that every subdirectory of api/ can be referenced by module namespacing and we don't have to write dune files for every route (or pages) folder. However, the OCaml LSP does not like it and red squiggles will show up in the editor (although the app with still compile without errors). Trying to develop the app knowing those red squiggles cannot be vanquished would drive me nuts, so instead of using (include_subdirs qualified) I just wrote dune files for every route (and page) which gets rid of the red squiggles.

2) Neither would having all source/targets specified, as that would entail listing them all in the dune file as wildcard rules is apparently still not a thing: https://github.com/ocaml/dune/issues/307

There is a small example on the dune home page: https://dune.build/

Dune (https://dune.build/) is the preeminent build tool for OCaml development. I don't love its input syntax (s-expressions), and I sometimes miss the ability to write high-level functions to reduce boilerplate (especially for unit tests), but it always gets the dependencies right, and it's fast. This is in stark contrast to some of my experiences with various other build systems, and I am super happy that the default option for OCaml build systems is so good.

It's still weird because dune's own site only makes Jane Street references: https://dune.build/.

ONE of the big benefits of OCaml is its powerful REPL (also called the toplevel), the interactive command-line utility where you can load modules, type in and execute code, and see its results. The modern REPL, utop, has powerful auto-completion and integration with the build system dune, which enables productive workflows like loading an entire project's libraries in the REPL and interactively exploring them.