WASM support

[A5rocks]

To be concrete: support for the emscripten build of CPython and pyodide.

It would be really cool :3

I mean, it would also indicate that our basic IO manager protocol is good enough to stabilize if we can implement such a strange architecture.

I'm not sure how testing would work nor whether anyone would use it. Also I'm not sure concretely what we can support:

• obviously we can manage sleeping and rescheduling
• sockets isn't possible AFAIK? I guess there's those WASI things.
• does pyodide provide a virtual file system or something? Maybe WASI does?

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Unless... Trio already works due to some compatibility things done by CPython? I am 95% it doesn't work though. At least I should figure out how tests would work.

[CoolCat467]

On https://pyodide.org/en/stable/console.html (had to hack the script to use v0.28.0 instead of 0.28.1)

>>> import micropip
>>> await micropip.install("trio")
>>> import trio
Traceback (most recent call last):
  File "<console>", line 1, in <module>
  File "/lib/python3.13/site-packages/trio/__init__.py", line 22, in <module>
    from ._core import TASK_STATUS_IGNORED as TASK_STATUS_IGNORED  # isort: split
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/lib/python3.13/site-packages/trio/_core/__init__.py", line 21, in <module>
    from ._local import RunVar, RunVarToken
  File "/lib/python3.13/site-packages/trio/_core/_local.py", line 9, in <module>
    from . import _run
  File "/lib/python3.13/site-packages/trio/_core/_run.py", line 3004, in <module>
    raise NotImplementedError("unsupported platform")
NotImplementedError: unsupported platform

So kind of success so far, can install at least, but needs work of course

[davidbrochart]

Maybe you just want to run a trio event loop on its own as a first step, but it's worth mentioning that pyodide integrates asyncio into the JavaScript event loop here. That allows e.g. JavaScript to await a Python task.

[A5rocks]

I would expect we don't need any special support in pyodide because of trio.lowlevel.wait_task_rescheduled (for Python awaiting JS) and the other way around is probably simple to do with plain JS promises.

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So kind of success so far, can install at least, but needs work of course

Yeah, I think that means we don't have an IO manager for it.