I am a Python programmer. I love Astral; I think Ruff is great and uv is life-changing, but I don't actually like ty that much.
I want my type checker to check types and to scream at me when it can't. I don't want it to do "gradual typing", if it is unsure about what type something is, I want that to be a failure instead of it modeling the unsureness and not showing potential errors. We live in the age of agents, having to add an extra annotation here and there is not so much of a problem any more.
Meta's Pyrefly largely does what I want. I don't quite love Pyrefly either; I don't like the fact that it edge-cases and gives monopoly status to some popular packages (Pydantic, Django, attrs) instead of offering generalized mechanisms that less popular packages could also utilize, but purely on a type checking front, it's excellent.
I want my type checker to check types and to scream at me when it can't. I don't want it to do "gradual typing", if it is unsure about what type something is, I want that to be a failure instead of it modeling the unsureness and not showing potential errors. We live in the age of agents, having to add an extra annotation here and there is not so much of a problem any more.
Meta's Pyrefly largely does what I want. I don't quite love Pyrefly either; I don't like the fact that it edge-cases and gives monopoly status to some popular packages (Pydantic, Django, attrs) instead of offering generalized mechanisms that less popular packages could also utilize, but purely on a type checking front, it's excellent.