Source code for returns.pointfree.alt

from typing import Callable, TypeVar

from returns.interfaces.altable import AltableN
from import Kinded, KindN, kinded

_FirstType = TypeVar('_FirstType')
_SecondType = TypeVar('_SecondType')
_ThirdType = TypeVar('_ThirdType')
_UpdatedType = TypeVar('_UpdatedType')

_AltableKind = TypeVar('_AltableKind', bound=AltableN)

[docs]def alt( function: Callable[[_SecondType], _UpdatedType], ) -> Kinded[Callable[ [KindN[_AltableKind, _FirstType, _SecondType, _ThirdType]], KindN[_AltableKind, _FirstType, _UpdatedType, _ThirdType], ]]: """ Lifts function to be wrapped in a container for better composition. In other words, it modifies the function's signature from: ``a -> b`` to: ``Container[a] -> Container[b]`` This is how it should be used: .. code:: python >>> from import IOFailure, IOSuccess >>> from returns.pointfree import alt >>> def example(argument: int) -> float: ... return argument / 2 >>> assert alt(example)(IOSuccess(1)) == IOSuccess(1) >>> assert alt(example)(IOFailure(4)) == IOFailure(2.0) Note, that this function works for all containers with ``.alt`` method. See :class:`returns.primitives.interfaces.altable.AltableN` for more info. """ @kinded def factory( container: KindN[_AltableKind, _FirstType, _SecondType, _ThirdType], ) -> KindN[_AltableKind, _FirstType, _UpdatedType, _ThirdType]: return container.alt(function) return factory