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from collections.abc import Callable
from typing import TypeVar
from returns.interfaces.applicative import ApplicativeN
from returns.primitives.hkt import Kinded, KindN, kinded
_FirstType = TypeVar('_FirstType')
_SecondType = TypeVar('_SecondType')
_ThirdType = TypeVar('_ThirdType')
_UpdatedType = TypeVar('_UpdatedType')
_ApplicativeKind = TypeVar('_ApplicativeKind', bound=ApplicativeN)
def apply(
container: KindN[
_ApplicativeKind,
Callable[[_FirstType], _UpdatedType],
_SecondType,
_ThirdType,
],
) -> Kinded[
Callable[
[KindN[_ApplicativeKind, _FirstType, _SecondType, _ThirdType]],
KindN[_ApplicativeKind, _UpdatedType, _SecondType, _ThirdType],
]
]:
"""
Turns container containing a function into a callable.
In other words, it modifies the function
signature from:
``Container[a -> b]``
to:
``Container[a] -> Container[b]``
This is how it should be used:
.. code:: python
>>> from returns.pointfree import apply
>>> from returns.maybe import Some, Nothing
>>> def example(argument: int) -> int:
... return argument + 1
>>> assert apply(Some(example))(Some(1)) == Some(2)
>>> assert apply(Some(example))(Nothing) == Nothing
>>> assert apply(Nothing)(Some(1)) == Nothing
>>> assert apply(Nothing)(Nothing) == Nothing
Note, that this function works for all containers with ``.apply`` method.
See :class:`returns.interfaces.applicative.ApplicativeN` for more info.
"""
@kinded
def factory(
other: KindN[_ApplicativeKind, _FirstType, _SecondType, _ThirdType],
) -> KindN[_ApplicativeKind, _UpdatedType, _SecondType, _ThirdType]:
return other.apply(container)
return factory
|
