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Comment by zeotroph | Hacker News Reader

There is also the rarely mentioned pytype from Google, written in Python. And pyright from Microsoft is written in Typescript, pyre at Facebook in OCaml. Last time I checked, these had better type inference algorithms (Hindley-Milner?) than mypy.

https://github.com/google/pytype https://github.com/google/pytype https://github.com/microsoft/pyright

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In my experience Hindley Milner type inference is a misfeature. Pyright doesn't use it and its typing system is very good. My only typing complaint with it is that it exactly types dict literals by default, which is usually not what you want.

By that I mean if you do

  foo = {"a": 2}
  foo["b"] = 3

you will get a type error because the inferred type of foo includes knowledge of the keys. But well written code doesn't use dicts when you know which keys are going to be present - you use a dataclass.

I guess you could argue most Python is not well written, but then most Python developers are too amateur to use Pyright anyway.

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