[Typing-sig] Re: PEP 593: Flexible function and variable annotations

On Sat, May 25, 2019 at 12:07 AM Vincent Siles vincent.siles+pyty@gmail.com wrote:

If my understanding is correct, a type-checker will have to parse the whole annotation payload to decide if it supports it or not. That's seems a bit too complicated, doesn't it ? Shouldn't we add a label (like `Annotated[T, 'feature name', X]`, with type alias to shorten the whole thing if need be) to make this decision easier ?

But ISTM the type-checker has to parse the whole payload regardless. Can you elaborate an example of an annotation payload that would be a burden for the type-checker to parse?