[nazgul17]

That's the dream. Reality is very different. Mypy presents numerous false negatives and false positives. Useful to screen for some bugs, but definitely far from giving guarantees.

Not to mention, if a library does not or does sloppily use type annotations, you would not get reliability even with a perfect type checker.

[globular-toast]

Sure but you can also write bugs in a perfectly typed compiled language. Short of formal verification the best we can do is try to minimise the possible surface for errors to occur. I'm of the opinion that language and tooling plays only a small part in writing robust software. What's more important is designing software using simple components that are small enough to be obviously correct.

[linsomniac]

I'm sure you're right that there are situations where mypy or ty or LSP give false positives/negatives, but in my use of them over the last ~6 months I really haven't run into many of those situations, or at least none come to mind. Libraries without type annotations do reduce the effectiveness to just what can be inferred by the type checker.

[wiz21c]

you need to work on big project for these flaws to become a problem. Say, you have a huge code base, 100000's of lines that you didn't write. Then you want to refactor a method's name. Python can't give you any guarantee the refactoring is fully complete. Only a real typed language can do that.

I write 95% of my code in python, I love it, it's my go to language for many things. But for huge code base which I don't master, the lack of type system makes me more than nervous.