Hacker News Reader

Comment by simonw | Hacker News Reader

Pyodide is one of the hidden gems of the Python ecosystem. It's SO good at what it does, and it's nearly 8 years old now so it's pretty mature.

I love using Pyodide to build web UIs for trying out new Python libraries. Here's one I built a few weeks ago to exercise my pure-Python SQLite AST parser, for example: https://tools.simonwillison.net/sqlite-ast

It's also pretty easy[1] to get C or Rust libraries that have Python bindings compiled to a WebAssembly wheel that Pyodide can then load.

Here's a bit of a nutty example - the new Monty Python-like sandbox library (written in Rust) compiled to WASM and then loaded in Pyodide in the browser: https://simonw.github.io/research/monty-wasm-pyodide/pyodide...

[1] OK, Claude Code knows how to do it.

View on HN

The who python web feels underused to be honest.

Maybe if browsers start shipping or downloading WASMs for python and others on request. And storing them for all sites going forward. Similar to how uv does it for for venvs it creates, there are standalone python version blobs.

At the same time it feels like the python is overused.

If I could wave a magic wand to reset any programming language adoption at this point I would choose Python over Javascript.

I think Pythons execution model, deep OO behaviour, and extremely weak guarantees have done a lot of damage to the soundness and performance of the technology world.

python at least won't cast numbers to strings when adding them.

JS doesn't either... JS casts numbers to strings when adding them to a string... "2" is not a number, it's a string that contains a number character... "2" + 2 === "22" because you are appending a number to a string, the cast is implicit and not really surprising if you understand what is going on.

Even more so when you consider how falsy values work in practice (data validation becomes really easy), there are a few gotchas, but in general they are pretty easily avoided in practice. JS is really good at dealing with garbage input in ways that don't blow up the world... sometimes that's a bad thing, but in practice it can also be a very good thing. But in the end it's a skill issue regarding understanding far more than a deep flaw. Not that there aren't flaws in JS... I think Date's in particular can be tough to deal with... a string vs a String instance is another.

What do you mean by "extremely weak guarantees"?

I recently learned that with this you can run juypter notebooks in your browser:

https://jupyter.org/try-jupyter/lab/

Stuff like numpy seems to just work

How do you call those C/Rust libraries compiled from to webassembly from Python/Pyodide?

You have to turn them into WebAssembly wheels, then you can import them as if they were regular Python modules.

Could you share the UI repo? This is really interesting stuff.

Should be this one https://github.com/simonw/research/blob/main/monty-wasm-pyod...

Thanks!

Serious question: why would you use Python on the web? Unless you have some legacy code that you want to reuse. Performance is somehow worse than CPython, C-extensions are missing, dev experience is atrocious.

The web is the only major platform that has a language monoculture to its detriment (i.e., not all problems are Javascript shaped). IMO the web ought to become multilingual (and become JS optional_ to further ensure its continued longevity and agility. Hopefully one day browser vendors will offer multiple runtime downloads (or something similar capability).

> i.e., not all problems are Javascript shaped

I’m having trouble coming up with a single Python-shaped problem that can’t be contained within JavaScript-shaped ecosystem.

WASM already offers this, for better or worse... There should be improved interop APIs for DOM access, but WASM is already very useful and even for directed UI control, "fast enough" a lot of the time. Dioxus, Yew and Leptos are already showing a lot of this to be good enough. That said, I would like to see a richer component ecosystem.

Embedded systems, consoles and mobile phones come to mind as well.

Even if you can go outside the blessed languages, it isn't without pain and scars.

All the embedded systems I've worked in have many languages you can use to compile whatever, burn, and run whatever you like. Consoles run game engines and programs written in all sorts of different languages. They don't care as long as they can execute the binary. Phones can run apps using many different languages (C, C++, Rust, Python, etc.).

Failed to read my second sentence.

C extensions aren't missing, the key ones are available in Pyodide already and you can compile others to WASM wheels if you need them.

You use Python on the web because there's existing software written in Python that you want to run in a browser.

Reply on news.ycombinator.com