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|
from collections.abc import Callable
from typing import TypeVar
from returns.interfaces.bindable import BindableN
from returns.primitives.hkt import Kinded, KindN, kinded
_FirstType = TypeVar('_FirstType')
_SecondType = TypeVar('_SecondType')
_ThirdType = TypeVar('_ThirdType')
_UpdatedType = TypeVar('_UpdatedType')
_BindableKind = TypeVar('_BindableKind', bound=BindableN)
def bind(
function: Callable[
[_FirstType],
KindN[_BindableKind, _UpdatedType, _SecondType, _ThirdType],
],
) -> Kinded[
Callable[
[KindN[_BindableKind, _FirstType, _SecondType, _ThirdType]],
KindN[_BindableKind, _UpdatedType, _SecondType, _ThirdType],
]
]:
"""
Turns function's input parameter from a regular value to a container.
In other words, it modifies the function
signature from:
``a -> Container[b]``
to:
``Container[a] -> Container[b]``
Similar to :func:`returns.pointfree.lash`,
but works for successful containers.
This is how it should be used:
.. code:: python
>>> from returns.pointfree import bind
>>> from returns.maybe import Maybe, Some, Nothing
>>> def example(argument: int) -> Maybe[int]:
... return Some(argument + 1)
>>> assert bind(example)(Some(1)) == Some(2)
>>> assert bind(example)(Nothing) == Nothing
Note, that this function works for all containers with ``.bind`` method.
See :class:`returns.primitives.interfaces.bindable.BindableN` for more info.
"""
@kinded
def factory(
container: KindN[_BindableKind, _FirstType, _SecondType, _ThirdType],
) -> KindN[_BindableKind, _UpdatedType, _SecondType, _ThirdType]:
return container.bind(function)
return factory
|
