CoWasm: An alternative to Emscripten, based on Zig (demo: Python in the browser) (opens in new tab)

That's just incredibly cool, my congratulations!

Foremost, my apologies if this is a nonsensical question. I haven't been soaking in the WASM ecosystem enough to know how much WASM is "just" JS versus ... something else.

Caveat aside, I saw one of the commits mention jython, which notoriously has ancient (and probably incredibly incomplete) python 2.x support; do you know if python-wasm would run on top of GraalJS (https://github.com/oracle/graaljs#nodejs-support)?

Separately, do you want issues related to zython.org in the cowasm issue tracker? It returns 405 (method not allowed) over and over on POST https://zython.org/python-wasm-sw/read-signal for me

This is really cool, William! A lifetime ago, we were pondering what it would take to get Sage running in the browser from a static server. It feels like you're nearly there. Is that in the plans?

It feels really fast and responsive. Have you done any benchmarks to compare against other Pythons-in-the-browser?

Or 'normal' Python for that matter.

no questions, but please keep working on that. I'm very impressed with how smoothly the current cowasm implementation is working.

For the future do your have a plans to support WASI and other modern WebAssembly stuff (like WebAssembly Component Model support f.e)?

What pain points with emscriptem do you want to address? What are the trade-offs you’re considering?

I am using the Python ecosystem (with full support for dynamic loading of C extension modules) as an initial motivating project. Also, the Python test suite is extremely useful to root out problems. I certainly hope that this can provide a more complete alternative to Emscripten to the community eventually. That said, Emscripten is huge, and the problems involved in creating a more maintainable modular WASM build tool are subtle. For example, when implementing a custom module loader for Python-wasm last week, I discovered several bugs in the memfs and unionfs Javascript libraries (https://github.com/streamich/memfs/pulls?q=is%3Apr+author%3A... and https://github.com/streamich/unionfs/pulls?q=is%3Apr+author%...). I had to learn the code sufficiently to fix all these bugs, submit PR's, etc. Emscripten has its own analogue of memfs, which is optimized specifically for WebAssembly in the browser, where memfs is a more general widely used library (with 10M+ downloads/week).

CoWasm has no support for asyncify. Where I've run into setjmp/longjmp so far, I've been rewriting the code instead. E.g., the dash shell uses setjmp/longjmp, and I'm rewriting that to use return error codes instead (see, e.g., https://github.com/sagemathinc/dash/commit/7117e1f6496728af0...).

> how would I go about porting a simple C->WASM w/ Typescript library project to CoWasm?

That's a great question, which I'm not sure how to quickly answer, so I've created a discussion item here https://github.com/sagemathinc/cowasm/discussions/40 I did a massive refactor of the codebase during the last month, and it makes doing what you want much easier. However, it will help a lot once there are some good examples. I'm probably boing to individually package some of the things I've ported for CoWasm as standalone examples.

In any case, CoWasm is extremely open source (BSD 3-clause), and I strongly encourage anybody who is interested to grab a copy, build it, poke around, make a PR, etc.

This is a slim alternative to Emscripten which focuses only on the C/C++ <=> JS interoperability part:

https://github.com/schellingb/wajic

I don't think there are actual Emscripten replacements though which give you all the features, but in a 'cleaner' package. Emscripten does a lot on top of clang/llvm. A lot of the 'Emscripten magic' has been moved into the Binaryen tools though, so it can be used by other toolchains (like wajic): https://github.com/WebAssembly/binaryen.

Not yet, and it's not clear that's the goal, exactly. Up near the top, the README says CoWasm "goes far beyond just Python". Then later: "The goal of CoWasm is overall similar to all of emscripten, WebAssembly.sh, wapm.io, and Pyodide in various ways." But the "How does CoWasm compare to Emscripten and Pyodide?" section doesn't mention Emscripten.

looks like a duplicate, but it has no discussion. I'm not OP of either of these but I'd love for this to get to the top to foster a discussion about their approach (which seems exciting)

> There is no business unfriendly GPL code in CoWasm. CoWasm itself is extremely liberally licensed and business friendly.

This is one to save for posterity, when they eventually change the license because the likes of Amazon decided to make a product out of it.