mirror of https://github.com/astral-sh/ruff
b892e4548e
`Type::TypeVar` now distinguishes whether the typevar in question is
inferable or not.
A typevar is _not inferable_ inside the body of the generic class or
function that binds it:
```py
def f[T](t: T) -> T:
return t
```
The infered type of `t` in the function body is `TypeVar(T,
NotInferable)`. This represents how e.g. assignability checks need to be
valid for all possible specializations of the typevar. Most of the
existing assignability/etc logic only applies to non-inferable typevars.
Outside of the function body, the typevar is _inferable_:
```py
f(4)
```
Here, the parameter type of `f` is `TypeVar(T, Inferable)`. This
represents how e.g. assignability doesn't need to hold for _all_
specializations; instead, we need to find the constraints under which
this specific assignability check holds.
This is in support of starting to perform specialization inference _as
part of_ performing the assignability check at the call site.
In the [[POPL2015][]] paper, this concept is called _monomorphic_ /
_polymorphic_, but I thought _non-inferable_ / _inferable_ would be
clearer for us.
Depends on #19784
[POPL2015]: https://doi.org/10.1145/2676726.2676991
---------
Co-authored-by: Carl Meyer <carl@astral.sh>
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|---|---|---|
| .. | ||
| annotated.md | ||
| any.md | ||
| callable.md | ||
| deferred.md | ||
| int_float_complex.md | ||
| invalid.md | ||
| literal.md | ||
| literal_string.md | ||
| never.md | ||
| new_types.md | ||
| optional.md | ||
| self.md | ||
| starred.md | ||
| stdlib_typing_aliases.md | ||
| string.md | ||
| union.md | ||
| unsupported_special_forms.md | ||
| unsupported_special_types.md | ||
| unsupported_type_qualifiers.md | ||