16 – Type statements#
Since Python 3.12 that you can use type statements to create type aliases, which can also be generic.
For example, the statement below creates a type alias called Pair that holds pairs of values of the same type:
type Pair[T] = tuple[T, T]
This is much shorter than the equivalent pre-Python 3.12 code using typing.TypeAlias and typing.TypeVar:
from typing import TypeAlias, TypeVar
T = TypeVar("T")
Pair: TypeAlias = tuple[T, T]
For both versions of the code, the following assignment type-checks:
p: Pair[int] = (3, 4)
Further reading: