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Comment by jerrygenser | Hacker News Reader

Basedpyright is not rust but it's a fork of pyright with added features that are otherwise locked in vscode

It's written in Typescript, which is a super weird choice.

Wasn’t pyright made specifically for VSCode? That would explain TS.

Yes, but why they did not write it in a compiled language? Pyright is pretty slow in large code bases and takes a lot of RAM. Javascript can be faster than python in some cases, but Python is so easily extendable with C,C++, Cython, Rust. They could use Python with one of the compiled language.

Because they wanted it to be usable on the web, and I guess WASM wasn't where it is right now when they started.

It's also horrible for fasle positives unless your project happens to be the exact same setup as the maintainers' - I had to turn off the actual type checking on it. I've since moved wholesale to the Ty alpha and it feels a hell of a lot smarter.

It also inherits the unfortunate attitude of Pyright that it will warn against idiomatic Python (EAFP) in favour of non-idiomatic Python (LBYL):

https://github.com/microsoft/pyright/issues/1739

https://docs.python.org/3/glossary.html#term-EAFP

https://docs.python.org/3/glossary.html#term-LBYL

Eww, what? I hadn’t seen that before. Yikes, I hope the situation’s improved. I’d be butting into that continually.

Sometimes dynamic Python idioms are incompatible with typed Python. I personally think that's fine, since I consider static typing a significant improvement overall.

This isn’t. They actually fixed that bug. Then they changed their minds and backed the fix back out again because they don’t think you should write Python that way:

> I think EAFP is a very unfortunate and ill-advised practice.

They want you to not write the idiomatic Python:

    try:
        foo = bar["baz"]["qux"]
        ...
    except KeyError:
        ...

…and instead write the non-idiomatic version:

    if "baz" in bar and "qux" in bar["baz"]:
        foo = bar["baz"]["qux"]
        ...
    else:
        ...

If this were a linter then I would accept that it is going to be opinionated. But this is not a linter, it’s a type checker. Their opinions about EAFP are irrelevant. That’s idiomatic Python.

Well I agree with them. The second code is clearly better. Exceptions should be used for error handling and if those keys are actually optional then you should explicitly check if they exist (or use something like `bar.get("baz")`).

You are welcome to that opinion, but type checkers should not be opinionated, especially if they push people to write non-idiomatic Python. If you think this should be written a different way, that’s what lint rules are for.

Actually Python type checkers must be opinionated. Python doesn't define the semantics of type annotations so type checkers have to choose them.

They don't always choose the same options, so some Python code may type check in one type checker and not in another.

Yes this is a dumb situation but that's how it is. So Pyright has to make a choice here, and they chose the most sensible option.

You're free to disagree of course.

I'm sorry, I can't take seriously any piece of software which decided to prefix the previous version's name with "based". I'm aware this is a me problem.

Hah. I love the name. It implies that whatever the original “pyright” was doing wasn’t keepin’ it real. This new version, it’s “based” so it must be somehow more “real” and “grounded” and “legit”.

All I know is it is much more strict about stuff than pylance was.

Also a me problem!

Definitely this. I commend author of BPyright, but clown (?) avatar, unknown identity of maintainer, and name of the fork rub me off wrong way.

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