Merge wasm_of_ocaml

[OlivierNicole]

This aims to merge wasm_of_ocaml, currently hosted at https://github.com/ocaml-wasm/wasm_of_ocaml, back into this repo.

This is pending on Dune support ocaml/dune#11029. For now, Dune is pinned for the CI jobs.

[hhugo]

@vouillon, I'm testing 9b964d9 in #1757

[hhugo]

@vouillon, I'm testing 9b964d9 in #1757

I think you should cherry-pick cf96d62

[hhugo]

Thanks for all the hard work

[dbuenzli]

Bravo! Is there some high level docs on how to use the stuff ?

[vouillon]

Bravo! Is there some high level docs on how to use the stuff ?

There is a short README_wasm_of_ocaml.md. But I still need to write some documentation...

[rickyvetter]

Incredible! This is awesome.

[dbuenzli]

There is a short README_wasm_of_ocaml.md.

This looks to good to be true :–) The browsers APIs can be used as is ?

However it is possible to make it work over the file:// protocol ? And what's the story with webworkers ?

I have a number crunching app (computing thousands of polygon intersections) that I distribute as a single double-clickable .html file. It would be interesting to see the gains there. However it uses extremely dirty tricks to make webworkers work out of a single js_of_ocaml compiled file with code paths differentiated in the main via Worker.ami.

[vouillon]

The browsers APIs can be used as is ?

Right.

However it is possible to make it work over the file:// protocol ?

Not at the moment. Source Phase Imports might make it possible at some point. Or maybe we could have an option to somehow embed the Wasm code in the JavaScript code.

And what's the story with webworkers ?

I'm not sure. What problem could there be?

I have a number crunching app (computing thousands of polygon intersections) that I distribute as a single double-clickable .html file. It would be interesting to see the gains there. However it uses extremely dirty tricks to make webworkers work out of a single js_of_ocaml compiled file with code paths differentiated in the main via Worker.ami.

This might just work if we embed the Wasm code.

[dbuenzli]

I'm not sure. What problem could there be?

I'm concerned about data transfers. With webworkers you are supposed to transfer JavaScript values that that go through the structured clone algorithm.

As we once discussed that worked relatively flawlessly with js_of_ocaml's encoding of OCaml values encoded as JavaScript values.

Now I don't know how OCaml values are represented in wasm_of_ocaml, but in the webworker work queue I linked to I'm basically using Obj.magic on OCaml values to transfer work items but if those are no longer represented as JavaScript values then I expect kaboom.

[vouillon]

OCaml values are represented using Wasm GC values, so indeed the structured clone algorithm will not work on them. You have to serialize them somehow. You can try Marshal which works much better than with Js_of_ocaml (integers and floats do not share the same representation).

I have some experimental code to embed the Wasm code within the JavaScript code. Maybe you could give it a try.

[micahcantor]

Congrats @vouillon @OlivierNicole @hhugo 🎉 !