from __future__ import annotations
from typing import TYPE_CHECKING, Any, Callable, ClassVar, TypeVar, final
from returns.context import NoDeps
from returns.interfaces.specific import reader_ioresult
from returns.io import IO, IOFailure, IOResult, IOSuccess
from returns.primitives.container import BaseContainer
from returns.primitives.hkt import Kind3, SupportsKind3, dekind
from returns.result import Result
if TYPE_CHECKING:
from returns.context.requires_context import RequiresContext
from returns.context.requires_context_result import RequiresContextResult
# Context:
_EnvType = TypeVar('_EnvType', contravariant=True)
_NewEnvType = TypeVar('_NewEnvType')
# Result:
_ValueType = TypeVar('_ValueType', covariant=True)
_NewValueType = TypeVar('_NewValueType')
_ErrorType = TypeVar('_ErrorType')
_NewErrorType = TypeVar('_NewErrorType')
# Helpers:
_FirstType = TypeVar('_FirstType')
[docs]@final
class RequiresContextIOResult( # type: ignore[type-var]
BaseContainer,
SupportsKind3['RequiresContextIOResult', _ValueType, _ErrorType, _EnvType],
reader_ioresult.ReaderIOResultBasedN[_ValueType, _ErrorType, _EnvType],
):
"""
The ``RequiresContextIOResult`` combinator.
See :class:`returns.context.requires_context.RequiresContext`
and :class:`returns.context.requires_context_result.RequiresContextResult`
for more docs.
This is just a handy wrapper around
``RequiresContext[IOResult[a, b], env]``
which represents a context-dependent impure operation that might fail.
It has several important differences from the regular ``Result`` classes.
It does not have ``Success`` and ``Failure`` subclasses.
Because, the computation is not yet performed.
And we cannot know the type in advance.
So, this is a thin wrapper, without any changes in logic.
Why do we need this wrapper? That's just for better usability!
.. code:: python
>>> from returns.context import RequiresContext
>>> from returns.io import IOSuccess, IOResult
>>> def function(arg: int) -> IOResult[int, str]:
... return IOSuccess(arg + 1)
>>> # Without wrapper:
>>> assert RequiresContext.from_value(IOSuccess(1)).map(
... lambda ioresult: ioresult.bind(function),
... )(...) == IOSuccess(2)
>>> # With wrapper:
>>> assert RequiresContextIOResult.from_value(1).bind_ioresult(
... function,
... )(...) == IOSuccess(2)
This way ``RequiresContextIOResult`` allows to simply work with:
- raw values and pure functions
- ``RequiresContext`` values and pure functions returning it
- ``RequiresContextResult`` values and pure functions returning it
- ``Result`` and pure functions returning it
- ``IOResult`` and functions returning it
- other ``RequiresContextIOResult`` related functions and values
This is a complex type for complex tasks!
.. rubric:: Important implementation details
Due it is meaning, ``RequiresContextIOResult``
cannot have ``Success`` and ``Failure`` subclasses.
We only have just one type. That's by design.
Different converters are also not supported for this type.
Use converters inside the ``RequiresContext`` context, not outside.
See also:
- https://dev.to/gcanti/getting-started-with-fp-ts-reader-1ie5
- https://en.wikipedia.org/wiki/Lazy_evaluation
- https://bit.ly/2R8l4WK
- https://bit.ly/2RwP4fp
"""
__slots__ = ()
#: Inner value of `RequiresContext`
#: is just a function that returns `IOResult`.
#: This field has an extra 'RequiresContext' just because `mypy` needs it.
_inner_value: Callable[[_EnvType], IOResult[_ValueType, _ErrorType]]
#: A convenient placeholder to call methods created by `.from_value()`.
no_args: ClassVar[NoDeps] = object()
def __init__(
self,
inner_value: Callable[[_EnvType], IOResult[_ValueType, _ErrorType]],
) -> None:
"""
Public constructor for this type. Also required for typing.
Only allows functions of kind ``* -> *``
and returning :class:`returns.result.Result` instances.
.. code:: python
>>> from returns.context import RequiresContextIOResult
>>> from returns.io import IOSuccess
>>> str(RequiresContextIOResult(lambda deps: IOSuccess(deps + 1)))
'<RequiresContextIOResult: <function <lambda> at ...>>'
"""
super().__init__(inner_value)
def __call__(self, deps: _EnvType) -> IOResult[_ValueType, _ErrorType]:
"""
Evaluates the wrapped function.
.. code:: python
>>> from returns.context import RequiresContextIOResult
>>> from returns.io import IOSuccess
>>> def first(lg: bool) -> RequiresContextIOResult[int, str, float]:
... # `deps` has `float` type here:
... return RequiresContextIOResult(
... lambda deps: IOSuccess(deps if lg else -deps),
... )
>>> instance = first(False)
>>> assert instance(3.5) == IOSuccess(-3.5)
In other things, it is a regular Python magic method.
"""
return self._inner_value(deps)
[docs] def swap(
self,
) -> RequiresContextIOResult[_ErrorType, _ValueType, _EnvType]:
"""
Swaps value and error types.
So, values become errors and errors become values.
It is useful when you have to work with errors a lot.
And since we have a lot of ``.bind_`` related methods
and only a single ``.lash`` - it is easier to work with values.
.. code:: python
>>> from returns.context import RequiresContextIOResult
>>> from returns.io import IOSuccess, IOFailure
>>> success = RequiresContextIOResult.from_value(1)
>>> failure = RequiresContextIOResult.from_failure(1)
>>> assert success.swap()(...) == IOFailure(1)
>>> assert failure.swap()(...) == IOSuccess(1)
"""
return RequiresContextIOResult(lambda deps: self(deps).swap())
[docs] def map(
self, function: Callable[[_ValueType], _NewValueType],
) -> RequiresContextIOResult[_NewValueType, _ErrorType, _EnvType]:
"""
Composes successful container with a pure function.
.. code:: python
>>> from returns.context import RequiresContextIOResult
>>> from returns.io import IOSuccess, IOFailure
>>> assert RequiresContextIOResult.from_value(1).map(
... lambda x: x + 1,
... )(...) == IOSuccess(2)
>>> assert RequiresContextIOResult.from_failure(1).map(
... lambda x: x + 1,
... )(...) == IOFailure(1)
"""
return RequiresContextIOResult(lambda deps: self(deps).map(function))
[docs] def apply(
self,
container: Kind3[
RequiresContextIOResult,
Callable[[_ValueType], _NewValueType],
_ErrorType,
_EnvType,
],
) -> RequiresContextIOResult[_NewValueType, _ErrorType, _EnvType]:
"""
Calls a wrapped function in a container on this container.
.. code:: python
>>> from returns.context import RequiresContextIOResult
>>> from returns.io import IOSuccess, IOFailure
>>> def transform(arg: str) -> str:
... return arg + 'b'
>>> assert RequiresContextIOResult.from_value('a').apply(
... RequiresContextIOResult.from_value(transform),
... )(...) == IOSuccess('ab')
>>> assert RequiresContextIOResult.from_value('a').apply(
... RequiresContextIOResult.from_failure(1),
... )(...) == IOFailure(1)
>>> assert RequiresContextIOResult.from_failure('a').apply(
... RequiresContextIOResult.from_value(transform),
... )(...) == IOFailure('a')
>>> assert RequiresContextIOResult.from_failure('a').apply(
... RequiresContextIOResult.from_failure('b'),
... )(...) == IOFailure('a')
"""
return RequiresContextIOResult(
lambda deps: self(deps).apply(dekind(container)(deps)),
)
[docs] def bind(
self,
function: Callable[
[_ValueType],
Kind3[
RequiresContextIOResult,
_NewValueType,
_ErrorType,
_EnvType,
],
],
) -> RequiresContextIOResult[_NewValueType, _ErrorType, _EnvType]:
"""
Composes this container with a function returning the same type.
.. code:: python
>>> from returns.context import RequiresContextIOResult
>>> from returns.io import IOSuccess, IOFailure
>>> def first(lg: bool) -> RequiresContextIOResult[int, int, float]:
... # `deps` has `float` type here:
... return RequiresContextIOResult(
... lambda deps: IOSuccess(deps) if lg else IOFailure(-deps),
... )
>>> def second(
... number: int,
... ) -> RequiresContextIOResult[str, int, float]:
... # `deps` has `float` type here:
... return RequiresContextIOResult(
... lambda deps: IOSuccess('>=' if number >= deps else '<'),
... )
>>> assert first(True).bind(second)(1) == IOSuccess('>=')
>>> assert first(False).bind(second)(2) == IOFailure(-2)
"""
return RequiresContextIOResult(
lambda deps: self(deps).bind(
lambda inner: dekind( # type: ignore[misc]
function(inner),
)(deps),
),
)
#: Alias for `bind_context_ioresult` method, it is the same as `bind` here.
bind_context_ioresult = bind
[docs] def bind_result(
self,
function: Callable[[_ValueType], Result[_NewValueType, _ErrorType]],
) -> RequiresContextIOResult[_NewValueType, _ErrorType, _EnvType]:
"""
Binds ``Result`` returning function to the current container.
.. code:: python
>>> from returns.context import RequiresContextIOResult
>>> from returns.result import Failure, Result, Success
>>> from returns.io import IOSuccess, IOFailure
>>> def function(num: int) -> Result[int, str]:
... return Success(num + 1) if num > 0 else Failure('<0')
>>> assert RequiresContextIOResult.from_value(1).bind_result(
... function,
... )(RequiresContextIOResult.no_args) == IOSuccess(2)
>>> assert RequiresContextIOResult.from_value(0).bind_result(
... function,
... )(RequiresContextIOResult.no_args) == IOFailure('<0')
>>> assert RequiresContextIOResult.from_failure(':(').bind_result(
... function,
... )(RequiresContextIOResult.no_args) == IOFailure(':(')
"""
return RequiresContextIOResult(
lambda deps: self(deps).bind_result(function),
)
[docs] def bind_context(
self,
function: Callable[
[_ValueType],
RequiresContext[_NewValueType, _EnvType],
],
) -> RequiresContextIOResult[_NewValueType, _ErrorType, _EnvType]:
"""
Binds ``RequiresContext`` returning function to current container.
.. code:: python
>>> from returns.context import RequiresContext
>>> from returns.io import IOSuccess, IOFailure
>>> def function(arg: int) -> RequiresContext[int, str]:
... return RequiresContext(lambda deps: len(deps) + arg)
>>> assert function(2)('abc') == 5
>>> assert RequiresContextIOResult.from_value(2).bind_context(
... function,
... )('abc') == IOSuccess(5)
>>> assert RequiresContextIOResult.from_failure(2).bind_context(
... function,
... )('abc') == IOFailure(2)
"""
return RequiresContextIOResult(
lambda deps: self(deps).map(
lambda inner: function(inner)(deps), # type: ignore[misc]
),
)
[docs] def bind_context_result(
self,
function: Callable[
[_ValueType],
RequiresContextResult[_NewValueType, _ErrorType, _EnvType],
],
) -> RequiresContextIOResult[_NewValueType, _ErrorType, _EnvType]:
"""
Binds ``RequiresContextResult`` returning function to the current one.
.. code:: python
>>> from returns.context import RequiresContextResult
>>> from returns.io import IOSuccess, IOFailure
>>> from returns.result import Success, Failure
>>> def function(arg: int) -> RequiresContextResult[int, int, str]:
... if arg > 0:
... return RequiresContextResult(
... lambda deps: Success(len(deps) + arg),
... )
... return RequiresContextResult(
... lambda deps: Failure(len(deps) + arg),
... )
>>> assert function(2)('abc') == Success(5)
>>> assert function(-1)('abc') == Failure(2)
>>> assert RequiresContextIOResult.from_value(
... 2,
... ).bind_context_result(
... function,
... )('abc') == IOSuccess(5)
>>> assert RequiresContextIOResult.from_value(
... -1,
... ).bind_context_result(
... function,
... )('abc') == IOFailure(2)
>>> assert RequiresContextIOResult.from_failure(
... 2,
... ).bind_context_result(
... function,
... )('abc') == IOFailure(2)
"""
return RequiresContextIOResult(
lambda deps: self(deps).bind_result(
lambda inner: function(inner)(deps), # type: ignore[misc]
),
)
[docs] def bind_io(
self,
function: Callable[[_ValueType], IO[_NewValueType]],
) -> RequiresContextIOResult[_NewValueType, _ErrorType, _EnvType]:
"""
Binds ``IO`` returning function to the current container.
.. code:: python
>>> from returns.context import RequiresContextIOResult
>>> from returns.io import IO, IOSuccess, IOFailure
>>> def function(number: int) -> IO[str]:
... return IO(str(number))
>>> assert RequiresContextIOResult.from_value(1).bind_io(
... function,
... )(RequiresContextIOResult.no_args) == IOSuccess('1')
>>> assert RequiresContextIOResult.from_failure(1).bind_io(
... function,
... )(RequiresContextIOResult.no_args) == IOFailure(1)
"""
return RequiresContextIOResult(
lambda deps: self(deps).bind_io(function),
)
[docs] def bind_ioresult(
self,
function: Callable[[_ValueType], IOResult[_NewValueType, _ErrorType]],
) -> RequiresContextIOResult[_NewValueType, _ErrorType, _EnvType]:
"""
Binds ``IOResult`` returning function to the current container.
.. code:: python
>>> from returns.context import RequiresContextIOResult
>>> from returns.io import IOResult, IOSuccess, IOFailure
>>> def function(num: int) -> IOResult[int, str]:
... return IOSuccess(num + 1) if num > 0 else IOFailure('<0')
>>> assert RequiresContextIOResult.from_value(1).bind_ioresult(
... function,
... )(RequiresContextIOResult.no_args) == IOSuccess(2)
>>> assert RequiresContextIOResult.from_value(0).bind_ioresult(
... function,
... )(RequiresContextIOResult.no_args) == IOFailure('<0')
>>> assert RequiresContextIOResult.from_failure(':(').bind_ioresult(
... function,
... )(RequiresContextIOResult.no_args) == IOFailure(':(')
"""
return RequiresContextIOResult(
lambda deps: self(deps).bind(function),
)
[docs] def alt(
self, function: Callable[[_ErrorType], _NewErrorType],
) -> RequiresContextIOResult[_ValueType, _NewErrorType, _EnvType]:
"""
Composes failed container with a pure function.
.. code:: python
>>> from returns.context import RequiresContextIOResult
>>> from returns.io import IOSuccess, IOFailure
>>> assert RequiresContextIOResult.from_value(1).alt(
... lambda x: x + 1,
... )(...) == IOSuccess(1)
>>> assert RequiresContextIOResult.from_failure(1).alt(
... lambda x: x + 1,
... )(...) == IOFailure(2)
"""
return RequiresContextIOResult(lambda deps: self(deps).alt(function))
[docs] def lash(
self,
function: Callable[
[_ErrorType],
Kind3[
RequiresContextIOResult,
_ValueType,
_NewErrorType,
_EnvType,
],
],
) -> RequiresContextIOResult[_ValueType, _NewErrorType, _EnvType]:
"""
Composes this container with a function returning the same type.
.. code:: python
>>> from returns.context import RequiresContextIOResult
>>> from returns.io import IOSuccess, IOFailure
>>> def lashable(
... arg: str,
... ) -> RequiresContextIOResult[str, str, str]:
... if len(arg) > 1:
... return RequiresContextIOResult(
... lambda deps: IOSuccess(deps + arg),
... )
... return RequiresContextIOResult(
... lambda deps: IOFailure(arg + deps),
... )
>>> assert RequiresContextIOResult.from_value('a').lash(
... lashable,
... )('c') == IOSuccess('a')
>>> assert RequiresContextIOResult.from_failure('a').lash(
... lashable,
... )('c') == IOFailure('ac')
>>> assert RequiresContextIOResult.from_failure('aa').lash(
... lashable,
... )('b') == IOSuccess('baa')
"""
return RequiresContextIOResult(
lambda deps: self(deps).lash(
lambda inner: function(inner)(deps), # type: ignore
),
)
[docs] def compose_result(
self,
function: Callable[
[Result[_ValueType, _ErrorType]],
Kind3[
RequiresContextIOResult,
_NewValueType,
_ErrorType,
_EnvType,
],
],
) -> RequiresContextIOResult[_NewValueType, _ErrorType, _EnvType]:
"""
Composes inner ``Result`` with ``ReaderIOResult`` returning function.
Can be useful when you need an access to both states of the result.
.. code:: python
>>> from returns.context import ReaderIOResult, NoDeps
>>> from returns.io import IOSuccess, IOFailure
>>> from returns.result import Result
>>> def count(
... container: Result[int, int],
... ) -> ReaderIOResult[int, int, NoDeps]:
... return ReaderIOResult.from_result(
... container.map(lambda x: x + 1).alt(abs),
... )
>>> success = ReaderIOResult.from_value(1)
>>> failure = ReaderIOResult.from_failure(-1)
>>> assert success.compose_result(count)(...) == IOSuccess(2)
>>> assert failure.compose_result(count)(...) == IOFailure(1)
"""
return RequiresContextIOResult(
lambda deps: dekind(
function(self(deps)._inner_value), # noqa: WPS437
)(deps),
)
[docs] def modify_env(
self,
function: Callable[[_NewEnvType], _EnvType],
) -> RequiresContextIOResult[_ValueType, _ErrorType, _NewEnvType]:
"""
Allows to modify the environment type.
.. code:: python
>>> from returns.context import RequiresContextIOResultE
>>> from returns.io import IOSuccess, impure_safe
>>> def div(arg: int) -> RequiresContextIOResultE[float, int]:
... return RequiresContextIOResultE(
... impure_safe(lambda deps: arg / deps),
... )
>>> assert div(3).modify_env(int)('2') == IOSuccess(1.5)
>>> assert div(3).modify_env(int)('0').failure()
"""
return RequiresContextIOResult(lambda deps: self(function(deps)))
[docs] @classmethod
def ask(cls) -> RequiresContextIOResult[_EnvType, _ErrorType, _EnvType]:
"""
Is used to get the current dependencies inside the call stack.
Similar to :meth:`returns.context.requires_context.RequiresContext.ask`,
but returns ``IOResult`` instead of a regular value.
Please, refer to the docs there to learn how to use it.
One important note that is worth duplicating here:
you might need to provide ``_EnvType`` explicitly,
so ``mypy`` will know about it statically.
.. code:: python
>>> from returns.context import RequiresContextIOResultE
>>> from returns.io import IOSuccess
>>> assert RequiresContextIOResultE[int, int].ask().map(
... str,
... )(1) == IOSuccess('1')
"""
return RequiresContextIOResult(IOSuccess)
[docs] @classmethod
def from_result(
cls, inner_value: Result[_NewValueType, _NewErrorType],
) -> RequiresContextIOResult[_NewValueType, _NewErrorType, NoDeps]:
"""
Creates new container with ``Result`` as a unit value.
.. code:: python
>>> from returns.context import RequiresContextIOResult
>>> from returns.result import Success, Failure
>>> from returns.io import IOSuccess, IOFailure
>>> deps = RequiresContextIOResult.no_args
>>> assert RequiresContextIOResult.from_result(
... Success(1),
... )(deps) == IOSuccess(1)
>>> assert RequiresContextIOResult.from_result(
... Failure(1),
... )(deps) == IOFailure(1)
"""
return RequiresContextIOResult(
lambda _: IOResult.from_result(inner_value),
)
[docs] @classmethod
def from_io(
cls,
inner_value: IO[_NewValueType],
) -> RequiresContextIOResult[_NewValueType, Any, NoDeps]:
"""
Creates new container from successful ``IO`` value.
.. code:: python
>>> from returns.io import IO, IOSuccess
>>> from returns.context import RequiresContextIOResult
>>> assert RequiresContextIOResult.from_io(IO(1))(
... RequiresContextIOResult.no_args,
... ) == IOSuccess(1)
"""
return RequiresContextIOResult(
lambda deps: IOResult.from_io(inner_value),
)
[docs] @classmethod
def from_failed_io(
cls,
inner_value: IO[_NewErrorType],
) -> RequiresContextIOResult[Any, _NewErrorType, NoDeps]:
"""
Creates a new container from failed ``IO`` value.
.. code:: python
>>> from returns.io import IO, IOFailure
>>> from returns.context import RequiresContextIOResult
>>> assert RequiresContextIOResult.from_failed_io(IO(1))(
... RequiresContextIOResult.no_args,
... ) == IOFailure(1)
"""
return RequiresContextIOResult(
lambda deps: IOResult.from_failed_io(inner_value),
)
[docs] @classmethod
def from_ioresult(
cls, inner_value: IOResult[_NewValueType, _NewErrorType],
) -> RequiresContextIOResult[_NewValueType, _NewErrorType, NoDeps]:
"""
Creates new container with ``IOResult`` as a unit value.
.. code:: python
>>> from returns.context import RequiresContextIOResult
>>> from returns.io import IOSuccess, IOFailure
>>> deps = RequiresContextIOResult.no_args
>>> assert RequiresContextIOResult.from_ioresult(
... IOSuccess(1),
... )(deps) == IOSuccess(1)
>>> assert RequiresContextIOResult.from_ioresult(
... IOFailure(1),
... )(deps) == IOFailure(1)
"""
return RequiresContextIOResult(lambda _: inner_value)
[docs] @classmethod
def from_ioresult_context(
cls,
inner_value:
ReaderIOResult[_NewValueType, _NewErrorType, _NewEnvType],
) -> ReaderIOResult[_NewValueType, _NewErrorType, _NewEnvType]:
"""
Creates new container with ``ReaderIOResult`` as a unit value.
.. code:: python
>>> from returns.context import RequiresContextIOResult
>>> from returns.io import IOSuccess, IOFailure
>>> assert RequiresContextIOResult.from_ioresult_context(
... RequiresContextIOResult.from_value(1),
... )(...) == IOSuccess(1)
>>> assert RequiresContextIOResult.from_ioresult_context(
... RequiresContextIOResult.from_failure(1),
... )(...) == IOFailure(1)
"""
return inner_value
[docs] @classmethod
def from_typecast(
cls,
inner_value: RequiresContext[
IOResult[_NewValueType, _NewErrorType], _EnvType,
],
) -> RequiresContextIOResult[_NewValueType, _NewErrorType, _EnvType]:
"""
You might end up with ``RequiresContext[IOResult]`` as a value.
This method is designed to turn it into ``RequiresContextIOResult``.
It will save all the typing information.
It is just more useful!
.. code:: python
>>> from returns.context import RequiresContext
>>> from returns.io import IOSuccess, IOFailure
>>> assert RequiresContextIOResult.from_typecast(
... RequiresContext.from_value(IOSuccess(1)),
... )(RequiresContextIOResult.no_args) == IOSuccess(1)
>>> assert RequiresContextIOResult.from_typecast(
... RequiresContext.from_value(IOFailure(1)),
... )(RequiresContextIOResult.no_args) == IOFailure(1)
"""
return RequiresContextIOResult(inner_value)
[docs] @classmethod
def from_context(
cls, inner_value: RequiresContext[_NewValueType, _NewEnvType],
) -> RequiresContextIOResult[_NewValueType, Any, _NewEnvType]:
"""
Creates new container from ``RequiresContext`` as a success unit.
.. code:: python
>>> from returns.context import RequiresContext
>>> from returns.io import IOSuccess
>>> assert RequiresContextIOResult.from_context(
... RequiresContext.from_value(1),
... )(...) == IOSuccess(1)
"""
return RequiresContextIOResult(
lambda deps: IOSuccess(inner_value(deps)),
)
[docs] @classmethod
def from_failed_context(
cls, inner_value: RequiresContext[_NewValueType, _NewEnvType],
) -> RequiresContextIOResult[Any, _NewValueType, _NewEnvType]:
"""
Creates new container from ``RequiresContext`` as a failure unit.
.. code:: python
>>> from returns.context import RequiresContext
>>> from returns.io import IOFailure
>>> assert RequiresContextIOResult.from_failed_context(
... RequiresContext.from_value(1),
... )(...) == IOFailure(1)
"""
return RequiresContextIOResult(
lambda deps: IOFailure(inner_value(deps)),
)
[docs] @classmethod
def from_result_context(
cls,
inner_value: RequiresContextResult[
_NewValueType, _NewErrorType, _NewEnvType,
],
) -> RequiresContextIOResult[_NewValueType, _NewErrorType, _NewEnvType]:
"""
Creates new container from ``RequiresContextResult`` as a unit value.
.. code:: python
>>> from returns.context import RequiresContextResult
>>> from returns.io import IOSuccess, IOFailure
>>> assert RequiresContextIOResult.from_result_context(
... RequiresContextResult.from_value(1),
... )(...) == IOSuccess(1)
>>> assert RequiresContextIOResult.from_result_context(
... RequiresContextResult.from_failure(1),
... )(...) == IOFailure(1)
"""
return RequiresContextIOResult(
lambda deps: IOResult.from_result(inner_value(deps)),
)
[docs] @classmethod
def from_value(
cls,
inner_value: _NewValueType,
) -> RequiresContextIOResult[_NewValueType, Any, NoDeps]:
"""
Creates new container with ``IOSuccess(inner_value)`` as a unit value.
.. code:: python
>>> from returns.context import RequiresContextIOResult
>>> from returns.io import IOSuccess
>>> assert RequiresContextIOResult.from_value(1)(
... RequiresContextIOResult.no_args,
... ) == IOSuccess(1)
"""
return RequiresContextIOResult(lambda _: IOSuccess(inner_value))
[docs] @classmethod
def from_failure(
cls,
inner_value: _NewErrorType,
) -> RequiresContextIOResult[Any, _NewErrorType, NoDeps]:
"""
Creates new container with ``IOFailure(inner_value)`` as a unit value.
.. code:: python
>>> from returns.context import RequiresContextIOResult
>>> from returns.io import IOFailure
>>> assert RequiresContextIOResult.from_failure(1)(
... RequiresContextIOResult.no_args,
... ) == IOFailure(1)
"""
return RequiresContextIOResult(lambda _: IOFailure(inner_value))
# Aliases:
#: Alias for a popular case when ``Result`` has ``Exception`` as error type.
RequiresContextIOResultE = RequiresContextIOResult[
_ValueType, Exception, _EnvType,
]
#: Alias to save you some typing. Uses original name from Haskell.
ReaderIOResult = RequiresContextIOResult
#: Alias to save you some typing. Uses ``Exception`` as error type.
ReaderIOResultE = RequiresContextIOResult[_ValueType, Exception, _EnvType]