Comment by simonw

1 day ago

I've been looking forward to this for ages!

This means we can now take any C/Rust/whatever extension for Python, compile that as a `.wasm` extension, and then load it directly in browser Pyodide projects using:

  await micropip.install("package-on-pypi")
  import package_name

Here's how to try the new feature out. Visit https://pyodide.org/en/stable/console.html and type:

  import micropip
  await micropip.install("pydantic_core")
  import pydantic_core

That gets you this WASM wheel: https://pypi.org/project/pydantic_core/#pydantic_core-2.47.0...

You can tell that it's got compiled code in (and not just Python) by running:

  pydantic_core._pydantic_core

I get this:

  <module 'pydantic_core._pydantic_core' from '/lib/python3.14/site-packages/pydantic_core/_pydantic_core.cpython-314-wasm32-emscripten.so'>

6 comments

simonw

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simonw  1 day ago

I had an older experimental Pyodide WASM project lying around (a packaging of the Luau language by Roblox) so I had Codex package that up for me and pushed it to PyPI.

Here's the package: https://pypi.org/project/luau-wasm/

  import micropip
  await micropip.install("luau-wasm")
  import luau_wasm
  print(luau_wasm.execute(r'''
  local animals = {"fox", "owl", "frog", "rabbit"}
  table.sort(animals, function(a, b) return #a < #b end)
  for i, name in animals do print(i .. ". " .. name .. " (" .. #name .. ")") end
  '''))

And an interactive demo page where you can try it out: https://simonw.github.io/luau-wasm/

Wrote about this in more detail on my blog: https://simonwillison.net/2026/Jun/13/publishing-wasm-wheels...

willXare  21 hours ago

`await micropip.install()` is starting to feel dangerously close to "just ship the whole universe to the browser."

rtpg  18 hours ago

Is there any form of client-side caching that kicks in with all of this flow?

Tbh I don't feel great about people just writing up a bunch of scripts pulling things just on every run.

  • simonw  18 hours ago

    Browser caching works with stuff pulled from PyPI, so it shouldn't get loaded more than once.

westurner  1 hour ago

Here are all of the existing emscripten-forge recipes for building WASM packages: > jupyterlite-xeus supports environment.yml with jupyterlite with packages from emscripten-forge: https://jupyterlite-xeus.readthedocs.io/en/latest/environmen...

emscripten-forge was a Quetz repo built with but is now hosted on prefix.dev.

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