Draft: effects based on Typed continuation proposal

[vouillon]

No description provided.

[kayceesrk]

Exciting. Which engine do you have in mind for experimentation? CC @dhil.

[dhil]

Nice! We should be able to run this with https://github.com/wasmfx/wasmfxtime using the options wasmtime run -W=exceptions,function-references,typed-continuations file.{wast,wat,wasm} (you may want to build with cargo build --features=unsafe_disable_continuation_linearity_check to avoid materialising continuation objects as we do not garbage collect them yet). I am happy to help experiment with this and use it to performance tune our engine too (we need more benchmarks).

[kayceesrk]

Does https://github.com/wasmfx/wasmfxtime have GC support now?

[dhil]

Does https://github.com/wasmfx/wasmfxtime have GC support now?

The support is not complete yet. We are keeping in sync with upstream, where the GC support is being implemented. I think the structures are in place, so it should be possible to compile to it, but I don't think there is any actual runtime garbage collection yet.

[vouillon]

I did this a while ago when some basic support for typed continuations was added in binaryen, which allows to validate the Wasm code.

My motivation was mostly to have a feel of what an implementation of Ocaml effect handlers would look like.

I did not have any engine in mind for experimentation. One issue is that we rely quite a lot on JavaScript to implement some runtime features (like I/Os) at the moment.

[dhil]

I did this a while ago when some basic support for typed continuations was added in binaryen, which allows to validate the Wasm code.

My motivation was mostly to have a feel of what an implementation of Ocaml effect handlers would look like.

I did not have any engine in mind for experimentation. One issue is that we rely quite a lot on JavaScript to implement some runtime features (like I/Os) at the moment.

Presumably we can link in some WASI in place of the JS?

[kayceesrk]

@titzer suggested that we target https://github.com/titzer/wizard-engine. Wizard supports GC proposal, and the stack switching through typed continuations is in development: titzer/wizard-engine#175.

There is still the challenge of reliance on JS for runtime system features.

[vouillon]

We can probably develop a minimal runtime which is just able to support some effect benchmarks. That should not be too much work.