> That's currently impossible. It requires the component model[1] to be figured out...

Not really if you use C-APIs with 'primitive-type args' at the language boundaries, which is the same like in any other mixed-language scenario. Some languages make it harder to interact with C APIs than others, but that's a problem that needs to be fixed in those languages.

This. And as long as you provide memory allocation primitives, you can pass arbitrarily complex arguments in linear memory. It's just a matter of “ABI.”

The component model is already shipping in Wasmtime, and will be stable for use in Node.js and in browsers via jco (https://github.com/bytecodealliance/jco) soon. WASI Preview 2 will be done in December or January, giving component model users a stable set of interfaces to use for scheduling, streams, and higher level functionality like stdio, filesystem, sockets, and http on an opt-in basis. You should look at wit-bindgen (https://github.com/bytecodealliance/wit-bindgen) to see some of the languages currently supported, and more that will be mature enough to use very soon (https://github.com/bytecodealliance/componentize-py)

Right now jco will automatically generate the JS glue code which implements a Component Model runtime on top of the JS engine's existing WebAssembly implementation. So, yes, Components are a composition of Wasm Modules and JS code is handling passing values from one module/instance to another. You still get the performance benefits of running computation in Wasm.

One day further down the standardization road, we would like to see Web engines ship a native implementation of the Component Model, which might be able to make certain optimizations that the JS implementation cannot. Until then you can consider jco a polyfill for a native implementation, and it still gives you the power to compose isolated programs written in many languages and run them in many different contexts, including the Web.

(Disclosure: I am co-chair of WASI, Wasmtime maintainer, implemented many parts of WASI/CM)

Hm, ok so it seems there has finally been progress since I stopped looking (around a year ago, I was very actively following developments for a couple of years before that but got tired). I will check wit-bindgen and jco and see if I can finally make my little compiler emit code that can be called from other languages and vice versa without myself generating any JS glue code.

This isn't really true at a base level. You can do things like JS/Python interop now without this, eg: https://til.simonwillison.net/deno/pyodide-sandbox

It's possible all right, I've already done it. Imported Tesseract into Go with WASM.

https://news.ycombinator.com/item?id=38146154

It's not trivial because you have to figure out intricacies of the language and whatever compiled it into WASM, and Emscripten compiled WASM does expect some JS glue code. But WASM with WASI doesn't inherently require JS. And since Emscripten's JS glue is called via WASM host imports, you can implement them in whatever the host language is.