Re:Pyrefly v1.0.0 is here (Type Checker / Language Server fo...
by kinto on Wednesday May 13, 2026 @02:15PM
(#48125450)
Hi, Pyrefly developer here. It's been almost a year since our alpha has been released and we've been working hard towards a stable release. We're excited to announce general availability today!
Re:Pyrefly v1.0.0 is here (Type Checker / Language Server fo...
by kinto on Friday May 15, 2026 @10:18AM
(#48148937)
What type of deltas? We compare "conformance" on [this](https://pyrefly.org/blog/typing-conformance-comparison/) blog, which was a benchmark created by the creator of Pyright. However, it is quite specific to un-specified sections of PEP484 (things that checkers may not need to agree on but should). In terms of performance, you can see results [here](https://python-type-checking.com/typecheck_benchmark/) where we are quite a bit faster than pyright (almost 10x avg) and use far less memory (almost half).
Re:Pyrefly v1.0.0 is here (Type Checker / Language Server fo...
by ainch on Wednesday May 13, 2026 @05:52PM
(#48128109)
I'm glad it's 1.0, but for me the most exciting thing is the tensor shape typing they mention in the blogpost. I've been looking for a good solution to this for ages, and the Pyrefly implementation seems to have everything I'd like - incl. static typing (unlike jaxtyping's runtime-only setup), and shape inference (so passing a 2,3 tensor through a 3,10 linear layer gives you a 2,10 output tensor).
Re:Pyrefly v1.0.0 is here (Type Checker / Language Server fo...
by ducdetronquito on Thursday May 14, 2026 @03:17AM
(#48132112)
Congrats on the release, and thanks for this nice tool !
I migrated a small python/django backend project at work from basedpyright to pyrefly 1.0 yesterday to try it, and the migration was painless: just running pyrefly init converted the basedpyright config to a pyrefly config in the pyproject.toml.
The typecheking phase went from ~3/4s to 0.5s which is very nice when ran with pre-commit hooks. It also caught some unnecessary type conversion that basedpyright missed (ex: calling str(value) on a value that is already a string).
I haven't toyed too much with the LSP in zed, but I did not feel anything was missing for now.
I will try to migrate larger backends in the following weeks to see how it goes.
Anyway, it's very cool to see a new stable and fast typechecker for Python ! :)
See the official blog post for more details: https://pyrefly.org/blog/v1.0/
I migrated a small python/django backend project at work from basedpyright to pyrefly 1.0 yesterday to try it, and the migration was painless: just running pyrefly init converted the basedpyright config to a pyrefly config in the pyproject.toml.
The typecheking phase went from ~3/4s to 0.5s which is very nice when ran with pre-commit hooks. It also caught some unnecessary type conversion that basedpyright missed (ex: calling str(value) on a value that is already a string).
I haven't toyed too much with the LSP in zed, but I did not feel anything was missing for now.
I will try to migrate larger backends in the following weeks to see how it goes.
Anyway, it's very cool to see a new stable and fast typechecker for Python ! :)