extism VS reference-types

Extism can be really useful for packaging up and running cross-language libraries!

The most clear information about it is at: https://extism.org, but its a bit focused on the primary use case for Extism, being a universal plugin system.

There is a C PDK (https://github.com/extism/c-pdk) which you'd probably want to use in a new wrapper around your library in C++, and compile it to wasm32 freestanding or WASI, but without emscripten. Extism doesn't currently have an interop layer to emscripten.

It may just be my own unique obsession to peek at the internals of .wasm, but if anyone else is curious:

https://modsurfer.dylibso.com/module?hash=ab6f4b2de9db171347...

u/nbittich - curious if you've tried to use your language as as a scripting language inside other apps? I took a peak at your browser wasm environment, and think we could hook up the `compute` entrypoint you have here[0], but I'm not certain what the `ctx` does without going super deep, and if it could be passed into an Extism function[1] (which is how I'd try to run it from within 16+ other languages).

[0]: https://github.com/nbittich/adana/blob/master/adana-script-w...

[1]: https://github.com/extism/extism

Yep, this is one of the initial motivations for creating Extism: https://github.com/extism/extism -- and it works across 16 host languages & 8 guest languages.

On the devx, there's definitely some rough edges around building and using Wasm. My company has been working on a framework to ease integrating Wasm into existing applications. One area it focuses on is providing easy data passing between the host program and the Wasm and vice versa. https://github.com/extism/extism We do not have WASI preview 2 support yet, but are interested in integrating it.

Extism handles this really well across 16 or so different languages - and you don’t need to write a whole IDL / schema.

https://github.com/extism/extism

It’s a general purpose framework for building with WebAssembly and sharing code across languages is a great way to put it to work.

> It could be an interesting use case for WASM if the problem of passing data into the WASM VM cheaply (perhaps by reference) can be solved.

WASM Reference Types should hopefully solve this. The WASM working group seems to have some good momentum - so I'm hopeful this (or a similar replacement spec) will land sooner rather than later.

https://github.com/WebAssembly/reference-types/blob/master/p...

AFAIK GC is irrelevant for "direct DOM access", you would rather want to hop into the following rabbit hole:

- reference types: https://github.com/WebAssembly/reference-types/blob/master/p...

- interface types (inactive): https://github.com/WebAssembly/interface-types/blob/main/pro...

- component model: https://github.com/WebAssembly/component-model

If this looks like a mess, that's because it is. Compared to that, the current solution to go through a Javascript shim doesn't look too bad IMHO.

[1]: https://github.com/WebAssembly/proposals

A glance of the overview and spec seems to indicate that WASM will provide some primitive data types, and any GC language can build their implementation on top of it. As I understand it, it's heavily based on Reference Types[3], which allows acting on host-provided types, and is already considered part of the spec [4]. It doesn't remove the need for the 5 different runtimes to have their own GC, but it lowers the bulk that the runtimes need to carry around, and offloads some of that onto the WASM runtime instead.

[3]: https://github.com/WebAssembly/reference-types/blob/master/p...

They've talked about interface types, and added reference types, which is a stepping stone toward the GC extension proposal, which would be a stepping stone toward manipulating the DOM from the WebAssembly side, but their official roadmap page is more short-term.

Nope, WASM reference types, it has nothing to do with .NET type system.

> And there's been talk of exposing the JS GC to wasm for a few years. Hopefully when that stuff lands, it'll get easier to marshal objects across the gap.

You don't need a Wasm GC to do this. If you only need js objects to pass on to, say, the host's function or check is null or not, then reference types that are opaque external references: https://github.com/WebAssembly/reference-types/blob/master/p...

You can even do many more things if you export `Reflect` to WebAssembly: https://github.com/AssemblyScript/assemblyscript/blob/main/t...

Reference Types are available almost everywhere already (In Safari will be available after 15.0): https://webassembly.org/roadmap

Re: GC -- yes, indeed, the whole business with safepoints arose from the need to support Wasm reference types as a backend for Wasmtime or Firefox. No safepoints are needed for Rust (or other C-like) code.

Reference Types,