[Python-Dev] Re: Suggestion: a little language for type definitions

On Sat, Jan 08, 2022 at 12:32:35PM +0200, Serhiy Storchaka wrote:

08.01.22 01:59, jack.jansen@cwi.nl пише:

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If I can make a wild suggestion: why not create a little language for type specifications?

We need a way to define aliases. For example, write:

Data = Mapping[str, Sequence[Tuple[int, T]]] Factory = Callable[[int, Iterable[str]], Optional[list[Data[T]]]]

Can't we already do that? https://docs.python.org/3/library/typing.html#type-aliases Type aliases are great. But there are times where we don't want to write an alias when we can just write the type in-place, just as there are times where we don't want to write a function when we can just use an in-place expression. -- Steve