[xixixao]

In case you’re not well versed in Python typecheckers, in the mypy vs Pyright example, Pyright can be configured to complain about not annotating the collection (and so both typecheckers will yell at the code as written).

TypeScript takes the same approach in this scenario, and I assume this helps both be fast.

[solvedd]

They were "on the Python Typing Council and helped put together the spec, the conformance test suite, etc" so I assume they are an expert on Python typecheckers

[xixixao]

I didn’t write it for parent lol. I guess I should be more careful with “you”.

[jitl]

TypeScript will use flow typing to determine the type as number[] in this code:

    const x = []
    x.push(1)
    type t = typeof x // number[]