Comment by kingkongjaffa
Comment by kingkongjaffa 2 months ago
This is very cool but why wouldn’t they just contribute to uv and ruff and ty https://github.com/astral-sh/ty
Comment by kingkongjaffa 2 months ago
This is very cool but why wouldn’t they just contribute to uv and ruff and ty https://github.com/astral-sh/ty
The current major type checkers, mypy and pyright, are also based on the same PEPs, but you can still see differences between them. For example, my codebase passes pyright in strict mode, but mypy results in a bunch of type errors. I'd expect pyrefly and ty to be slightly different from each other.
See also:
https://github.com/microsoft/pyright/blob/main/docs/mypy-com...
https://htmlpreview.github.io/?https://github.com/python/typ...
Sure, I agree. I’m just saying that most of their defacto disagreements are because of ambiguity in the specs, not because one of them is (intentionally) choosing to fork.
Fwiw I think performance and features are kind of intertwined here, since Pyright’s extra speed makes it possible to infer more things that are not easy for mypy, especially in an LSP implementation.
Pyright is very impressive in that second link (conformance check), very much a product of Eric Traut & others dedicating a lot of energy to this single problem.
the specs are still evolving, and the various type checker implementations are what is driving them forward. in general, capturing the dynamic typing semantics of python in a gradually typed system is not a fully solved problem, and the type checkers are experimenting with various approaches to it.
I tend to agree.
I don't know the differences between the two well enough to know if it was the case here, but in my experience sometimes you need to innovate on a fork, or from scratch in order to create the space/freedom to do so.
Once a project is popular, it's harder to justify and be confident about major changes (aka https://m.xkcd.com/1172/)
It seems like the share a lot of the same goals but my impression is Poetry is much slower to pick up on standards. It’s normal to use uv with a project now that doesn’t have any [tool.uv] section in pyproject.toml at all but every poetry project I’ve seen is littered with [poetry] sections, even dependencies. Makes me not want to use it
I just ran ty and it can't resolve any imports whereas pyrefly passes. Why would that be? I hate Python so much.
ty doesn't invoke a Python interpreter to discover imports yet — so you need to either set `VIRTUAL_ENV` or pass `--python` to configure your target environment. We'll expand support here in the future, but this part of ty's interface is intentionally minimal while we focus on core type checking features.
I just put __init__.py everywhere, not sure it does something but to be safe
Because this has been tested at Meta / Facebook scale which means it's faster for any Python codebase massive and small.
Since Meta built this, I have confidence this will be maintained more than others and I will use this and ask for Pyrefly experience in the future.
I think astral and meta were both working on their own type-checkers independently. My current understanding is that meta released so they could preempt the initial release of ty. It seems like they're a bit further ahead in development. Not sure if there are going to be any real differences between the two down the line.