wasm support

[samuelcolvin]

I really want pydantic-core to support wasm. This is mostly so that the examples in pydantic's docs can be edited and run in the browser, but also for wider use of pydantic.

As per PyO3/pyo3#2412 (comment), it looks like it should be possible.

But I'm not sure how to integrate that with maturin github actions. @messense any pointers? Or would you be willing to submit a PR?

Also, as well as getting wheels to build, what more do we need to do to get pydantic-core working with pyiodide?

[hoodmane]

The next release of Pyodide will be able to load binary wheels with micropip. Hopefully we'll have an alpha release in the next few days.

[samuelcolvin]

Woop Woop, that's great news. Thanks @hoodmane.

[hoodmane]

I am happy to help out with CI. I am still trying to get improvements for the emscripten target into Rust. If they merge a few more PRs it will significantly simplify the complexity of the flags needed to build Rust code. Though I suppose that is all handled by maturin so it probably won't affect you directly.
https://github.com/rust-lang/rust/pulls?q=author%3Ahoodmane

There are also some warts in Pyodide, namely that we make it strangely hard to install a wheel from the local Emscripten filesystem with micropip which is really desirable for running unit tests.

pyodide/pyodide#2731

[messense]

#110 added the emscripten wheel building part, I'd wait for a new pyodide release to add the pytests part.

[samuelcolvin]

#110 looks great, just one tiny suggestion and otherwise we can merge it.

Since pypi won't at present accept wasm wheels, could we add those files (and indeed all wheels) to the release in github? Then it looks from micropip's docs like we could install pydantic-core from the github URL?

@hoodmane do you know of any other projects running unit tests with wasm/pyiodide? Might be a useful starting point to add the target to the test step of CI.

[samuelcolvin]

Is there anything else we need to do in this repo for this?

[hoodmane]

How about let's keep this open until we release the stable Pyodide v0.21.0. I expect to come back with some improvements in v0.21.0a3.

[samuelcolvin]

Sounds good.

[hoodmane]

Fix for the terminal output:
emscripten-core/emscripten#17320

[hoodmane]

I got all the plugins working:

[samuelcolvin]

amazing, what did you do about pytest-benchmark?