I would agree: the fact that `any` exists but cannot be used like `Any` is pretty confusing. But I do see that `any` vs. `Any` is semantically very different to `list` vs. `List`. I suggested the same thing on twitter https://twitter.com/samuel_colvin/status/1581590760993849344 a few months ago and got pretty universally shot down. Samuel -- Samuel Colvin On Tue, 22 Nov 2022 at 10:49, Thomas Kehrenberg wrote:

But wouldn't that be quite confusing because `any` is actually a function on bools, and not a type? _______________________________________________ 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: samcolvin@gmail.com

What about `callable` vs `Callable`? Was it already discussed? I don't think that you were shot down. You simply met a few people who didn't like the change. I think that the long term goal is to cover all typing use cases without a need for imports and that would be a step in this direction.

I'm -1 on 'any' for 'Any', but +0.5 on 'callable' for 'Callable' -- IIRC, Callable was the next most commonly used thing imported from typing (after, Dict, List etc. which were handled by PEP 585). On Wed, Nov 30, 2022 at 12:37 AM Shantanu Jain wrote:

Yes, that has been discussed, e.g. https://github.com/python/cpython/issues/86268

PEP 677 would have provided an alternative syntax for Callable, but the PEP was rejected.

In case anyone cares, my opinion on the matter is:

- builtins.any and typing.Any are too semantically different to share a symbol (you can subclass Any in 3.11!) - builtins.callable and typing.Callable are at least vaguely the same concept, so it's worth thinking about. For now I'm kind of -0 on it (and reserve the right to change my mind)... the status quo isn't terrible, callable is still somewhat different from Callable (unlike PEP 585 builtins), the import is not the worst thing about Callable, it may have a runtime cost, many IDEs have decent support for auto-importing, things may change (e.g. it would definitely have been a mistake if I'd made the change^^ and then PEP 677 had gotten accepted), etc

I wouldn't say it's a long term goal to cover all typing use cases without imports. In cases where static typing being bolted on to a 30 year old language causes a lot of usability pain, we should aspire to improve things. But dedicated syntax and changes to builtins are about the most far-reaching changes you can make to Python, so some circumspection is wise, potential costs are relatively high, potential benefits in this case are at most medium.

On Tue, 29 Nov 2022 at 23:43, Maciej M wrote:

...

What about `callable` vs `Callable`? Was it already discussed?

I don't think that you were shot down. You simply met a few people who didn't like the change. I think that the long term goal is to cover all typing use cases without a need for imports and that would be a step in this direction. _______________________________________________ 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: hauntsaninja@gmail.com

_______________________________________________ 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 van Rossum (python.org/~guido) *Pronouns: he/him **(why is my pronoun here?)* http://feministing.com/2015/02/03/how-using-they-as-a-singular-pronoun-can-c...

There's not much difference between the situation for `callable` and for, say, `list` though. Both are built-ins, and both continue to be valid when called: `callable(x)` and `list(x)` keep their meaning. PEP 585 added `list[itemtype]`, which was previously invalid; a new PEP could add `callable[[arg1, arg2, ...], ret]`, with a new meaning. The form `callable[...]` is currently *always* invalid (just like `list[...]` used to be); so it could be given a new meaning regardless of context. The main difficulty would seem to be that `callable(x)` needs to continue returning a bool. Given that *if* we were to do this, type checkers would have to special-case `callable` anyways (it's not a simple generic type like `list` -- `Callable` is also a special form), the special-casing could include "and if it's not subscripted, it's a boolean function". I have a feeling that this would be doable -- we have some other rather special forms, e.g. `type`, which can be used as `type(x)`, `type(name, bases, namespace)`, and `type[cls]`. I don't know about Pyright, but mypy certainly has plenty of references to "builtins.type" that make me think it special-cases the snot out of it, and whatever its definition in typeshed doesn't convey the desired semantics. I agree that there's no need to replace everything defined in typing.py with a builtin form; but PEP 677 (Callable Type Syntax) was proposed because it was the next most common special form after various things that were given built-in names by PEP 585. A substitute for `Any` is very low on the list (in part because its use is often a symptom of poorly typed code rather than of a missing typing feature). On Wed, Nov 30, 2022 at 9:13 PM Eric Traut wrote:

I'm -1 on both `any` and `callable`.

If the Python grammar distinguished clearly between type expressions and value expressions like most other languages, this would be feasible because the meaning of `any` and `callable` would be unambiguous from its syntactical position. However, there are many places in Python where a value expression is treated by a type checker as though it is a "type context". This includes cases like base classes in class declarations, bounds and constraints in TypeVar declarations, arguments to NewType, isinstance, cast, etc. Because of these cases, `any` and `callable` would be treated as their traditional builtin meaning by the runtime, and their meaning would be ambiguous for type checkers.

For this reason, I don't this proposal would work. Or it would require that the lowercase forms of `any` and `callable` would be usable only in certain places where type expressions are allowed, and developers would need to know which locations were OK and which were problematic. That would be really confusing.

I agree with Shantanu that it's not a goal to cover all typing use cases without imports, and I'm fine with requiring developers to import `Callable` and `Any`.

-Eric

-- Eric Traut Contributor to Pylance & Pyright Microsoft _______________________________________________ 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 van Rossum (python.org/~guido) *Pronouns: he/him **(why is my pronoun here?)* http://feministing.com/2015/02/03/how-using-they-as-a-singular-pronoun-can-c...

Whoops, I definitely misremembered that! It explains that people request something for Any too (but I don’t want to propose a similar hack there, you gave the reason exactly). But Callable is definitely the next highest on the list not yet covered, I didn’t misremember that. :-) —Guido On Wed, Nov 30, 2022 at 23:05 Shantanu Jain wrote:

...

Callable was the next most common special form after various things that were given built-in names by PEP 585. A substitute for `Any` is very low on the list

This isn't true, Any is used significantly more than Callable, see my comment in https://github.com/python/cpython/issues/86268#issuecomment-1093887929

Let's see if I can pull more up-to-date numbers...

- The corpus I'm using is https://github.com/hauntsaninja/mypy_primer (note that the corpus is much larger than it was two years ago^) - I'm searching for imports of the form `from typing import X, Y, Z` or `from collections.abc import X, Y, Z` (since that's now quite common!) - Search is done using the AST. I've attached code to this email, feel free to check or run on a corpus of your own. Numbers roughly line up to some grep spot checks. - Most of these projects use a type checker in CI — so I'd say "typically" typed, although you may still consider that "poor" ;-) - Full list of projects here https://github.com/hauntsaninja/mypy_primer/blob/master/mypy_primer.py#L954

Out of about 10,000 files that contain an import of this form:

Any: 5686 Optional: 3340 List: 2829 Dict: 2415 Callable: 2216 Tuple: 2000 Union: 1967 TYPE_CHECKING: 1817 cast: 1296 Sequence: 964 Iterable: 939 TypeVar: 815 Mapping: 754 Iterator: 617 Type: 614 Set: 515 Generator: 420 NamedTuple: 411 Literal: 384 overload: 312 Generic: 303 Final: 284 Awaitable: 246 TypedDict: 186 MutableMapping: 151 IO: 149 Coroutine: 147 Collection: 145 Hashable: 138 ClassVar: 130 NoReturn: 116 ... [longer tail of stuff] ...

On Wed, 30 Nov 2022 at 22:07, Guido van Rossum wrote:

...

There's not much difference between the situation for `callable` and for, say, `list` though. Both are built-ins, and both continue to be valid when called: `callable(x)` and `list(x)` keep their meaning. PEP 585 added `list[itemtype]`, which was previously invalid; a new PEP could add `callable[[arg1, arg2, ...], ret]`, with a new meaning.

The form `callable[...]` is currently *always* invalid (just like `list[...]` used to be); so it could be given a new meaning regardless of context.

The main difficulty would seem to be that `callable(x)` needs to continue returning a bool. Given that *if* we were to do this, type checkers would have to special-case `callable` anyways (it's not a simple generic type like `list` -- `Callable` is also a special form), the special-casing could include "and if it's not subscripted, it's a boolean function". I have a feeling that this would be doable -- we have some other rather special forms, e.g. `type`, which can be used as `type(x)`, `type(name, bases, namespace)`, and `type[cls]`. I don't know about Pyright, but mypy certainly has plenty of references to "builtins.type" that make me think it special-cases the snot out of it, and whatever its definition in typeshed doesn't convey the desired semantics.

I agree that there's no need to replace everything defined in typing.py with a builtin form; but PEP 677 (Callable Type Syntax) was proposed because it was the next most common special form after various things that were given built-in names by PEP 585. A substitute for `Any` is very low on the list (in part because its use is often a symptom of poorly typed code rather than of a missing typing feature).

On Wed, Nov 30, 2022 at 9:13 PM Eric Traut wrote:

...

I'm -1 on both `any` and `callable`.

If the Python grammar distinguished clearly between type expressions and value expressions like most other languages, this would be feasible because the meaning of `any` and `callable` would be unambiguous from its syntactical position. However, there are many places in Python where a value expression is treated by a type checker as though it is a "type context". This includes cases like base classes in class declarations, bounds and constraints in TypeVar declarations, arguments to NewType, isinstance, cast, etc. Because of these cases, `any` and `callable` would be treated as their traditional builtin meaning by the runtime, and their meaning would be ambiguous for type checkers.

For this reason, I don't this proposal would work. Or it would require that the lowercase forms of `any` and `callable` would be usable only in certain places where type expressions are allowed, and developers would need to know which locations were OK and which were problematic. That would be really confusing.

I agree with Shantanu that it's not a goal to cover all typing use cases without imports, and I'm fine with requiring developers to import `Callable` and `Any`.

-Eric

-- Eric Traut Contributor to Pylance & Pyright Microsoft _______________________________________________ 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 van Rossum (python.org/~guido) *Pronouns: he/him **(why is my pronoun here?)* http://feministing.com/2015/02/03/how-using-they-as-a-singular-pronoun-can-c... _______________________________________________ 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: hauntsaninja@gmail.com

...

-- --Guido (mobile)