On Wed, Dec 22, 2021 at 18:48 Gregory P. Smith <greg@krypto.org> wrote:
On Wed, Dec 22, 2021 at 3:24 PM Nathaniel Smith <njs@pobox.com> wrote:
On Wed, Dec 22, 2021 at 7:13 AM Steven Troxler <steven.troxler@gmail.com> wrote:
Pradeep, Guido and I are leaning toward removing the `async` part of
PEP 677.
There are several reasons: - If we leave `async` in, then `async (int) -> bool` and `(int) ->
- This violates that there should only be one obvious way to do
Awaitable[bool]` are the same things
- It also might lead to a mismatch between written types and the errors returned by type checkers, leading to unnecessary confusion - It looks like < 5% of callable types return Awaitable anyway - It has explicitly been brought up in python-dev as unnecessary complexity, and we largely agree with this criticism.
For sync programs, it doesn't matter what we do, because they'll never write `async` or `Awaitable`. For async programs, having to put `Awaitable` everywhere adds a lot of visual noise. Most Python programs are sync, so any async-related syntax is necessarily going to be rare in absolute terms, but that's not really the relevant audience to think about.
For modern code, `Awaitable` isn't used at definition point: you just write `async def foo(a: int) -> bool`. So keeping it in PEP 677 would make definition syntax and callable type syntax more consistent. I think it's a big win for usability.
I also don't think it violates "one obvious way" -- emphasis on "obvious" :-). With PEP 677 as currently written, using `async` everywhere is the "obvious" way; `Awaitable` becomes a detail that only type nerds have to think about.
While I agree with the overall philosophy here, the async keyword in annotation context is a syntax addition that could be deferred until after PEP 677 to appear in a later version.
As a side note, Awaitable is available from the typing module where typing users are already importing a pile from, as well as collections.abc. But they appear to be different things. Eek. `typing.Awaitable` vs `<class 'collections.abc.Awaitable'>`.
Really? They look closely related to me. What strikes you as different?
-gps
-n
-- Nathaniel J. Smith -- https://vorpus.org _______________________________________________ Typing-sig mailing list -- typing-sig@python.org To unsubscribe send an email to typing-sig-leave@python.org https://mail.python.org/mailman3/lists/typing-sig.python.org/ Member address: greg@krypto.org
_______________________________________________ Typing-sig mailing list -- typing-sig@python.org To unsubscribe send an email to typing-sig-leave@python.org https://mail.python.org/mailman3/lists/typing-sig.python.org/ Member address: guido@python.org
-- --Guido (mobile)