Source code for returns.converters
# -*- coding: utf-8 -*-
from typing import TypeVar, overload
from returns._generated import coalesce # noqa: WPS436
from returns.io import IO
from returns.maybe import Maybe
from returns.result import Failure, Result, Success
# Contianer internals:
_ValueType = TypeVar('_ValueType')
_ErrorType = TypeVar('_ErrorType')
# Re-export from generated:
coalesce_maybe = coalesce._coalesce_maybe # noqa: WPS437
coalesce_result = coalesce._coalesce_result # noqa: WPS437
[docs]def result_to_maybe(
result_container: Result[_ValueType, _ErrorType],
) -> Maybe[_ValueType]:
"""
Converts ``Result`` container to ``Maybe`` container.
.. code:: python
>>> from returns.maybe import Some, Nothing
>>> from returns.result import Failure, Success
>>> result_to_maybe(Success(1)) == Some(1)
True
>>> result_to_maybe(Failure(1)) == Nothing
True
>>> result_to_maybe(Success(None)) == Nothing
True
"""
return Maybe.new(result_container.value_or(None))
[docs]def maybe_to_result(
maybe_container: Maybe[_ValueType],
) -> Result[_ValueType, None]:
"""
Converts ``Maybe`` container to ``Result`` container.
.. code:: python
>>> from returns.maybe import Some, Nothing
>>> from returns.result import Failure, Success
>>> maybe_to_result(Nothing) == Failure(None)
True
>>> maybe_to_result(Some(1)) == Success(1)
True
>>> maybe_to_result(Some(None)) == Failure(None)
True
"""
inner_value = maybe_container.value_or(None)
if inner_value is not None:
return Success(inner_value)
return Failure(inner_value)
@overload
def join(container: IO[IO[_ValueType]]) -> IO[_ValueType]:
"""Case for ``IO`` container."""
@overload
def join(container: Maybe[Maybe[_ValueType]]) -> Maybe[_ValueType]:
"""Case for ``Maybe`` container."""
@overload
def join(
container: Result[Result[_ValueType, _ErrorType], _ErrorType],
) -> Result[_ValueType, _ErrorType]:
"""Case for ``Result`` container."""
[docs]def join(container):
"""
Joins two nested containers together.
.. code:: python
>>> from returns.maybe import Some
>>> from returns.result import Success
>>> from returns.io import IO
>>> join(IO(IO(1))) == IO(1)
True
>>> join(Some(Some(1))) == Some(1)
True
>>> join(Success(Success(1))) == Success(1)
True
"""
return container._inner_value # noqa: WPS437