⚙️ Result monad

This container wraps a result computation value into Ok or when the function call failed, returns Err(exception)

💻 API reference

ResultShortcutError

Bases: Exception, t.Generic[T_error]

Parameters:

Name	Type	Description	Default
Exception	_type_	description	required
t	_type_	description	required

Source code in fateful/monad/result.py

class ResultShortcutError(Exception, t.Generic[T_error]):
    """
    Args:
        Exception (_type_): _description_
        t (_type_): _description_
    """

    def __init__(self, error: T_error):
        super().__init__(error)
        self.error = error

result_shortcut(f)

summary

Parameters:

Name	Type	Description	Default
f	t.Callable[P_mapper, V]	description	required

Returns:

Type	Description
t.Callable[P, Result[T_co, T_error]]	t.Callable[P_mapper, Ok[V] | Err[t.Any]]: description

Source code in fateful/monad/result.py

def result_shortcut(
    f: t.Callable[P, Result[T_co, T_error]]
) -> t.Callable[P, Result[T_co, T_error]]:
    """
    _summary_

    Args:
        f (t.Callable[P_mapper, V]): _description_

    Returns:
        t.Callable[P_mapper, Ok[V] | Err[t.Any]]: _description_
    """

    def inner(*args: P.args, **kwargs: P.kwargs) -> Ok[T_co] | Err[T_error]:
        try:
            return Ok(f(*args, **kwargs))  # type: ignore[arg-type]
        except Exception as e:
            if isinstance(e, ResultShortcutError):
                return Err(e.error)
            raise

    return inner

sync_try(f, exc=(Exception))

Run a function that may raise an exception and return a Result type.

Parameters:

Name	Type	Description	Default
exc	tuple[type[T_err], ...]	description. Defaults to (Exception,)	(Exception)

Source code in fateful/monad/result.py

def sync_try(
    f: t.Callable[P, T_co],
    exc: type[T_error] | tuple[type[T_error], ...] = (Exception,),  # type: ignore
) -> t.Callable[P, Result[T_co, T_error]]:
    """
    Run a function that may raise an exception and return a Result type.
    Args:
        exc (tuple[type[T_err], ...], optional): _description_. Defaults to (Exception,)
    """

    def inner(*args: P.args, **kwargs: P.kwargs) -> Result[T_co, T_error]:
        try:
            return Ok(f(*args, **kwargs))
        except Exception as e:
            errors = exc if isinstance(exc, tuple) else (exc,)
            for err in errors:
                if isinstance(e, err):
                    return Err(e)
            raise

    return inner

to_result(exc=(Exception))

Decorator to convert a function that may raise an exception to a Result type.

Parameters:

Name	Type	Description	Default
exc	tuple[type[T_err], ...]	description. Defaults to (Exception,)	(Exception)

Returns:

Name	Type	Description
_type_	t.Callable[[t.Callable[P, T_co]], t.Callable[P, Result[T_co, T_error]]]	description

Source code in fateful/monad/result.py

def to_result(
    exc: type[T_error] | tuple[type[T_error], ...] = (Exception,)  # type: ignore
) -> t.Callable[[t.Callable[P, T_co]], t.Callable[P, Result[T_co, T_error]]]:
    """
    Decorator to convert a function that may raise an exception to a Result type.

    Args:
        exc (tuple[type[T_err], ...], optional): _description_. Defaults to (Exception,)

    Returns:
        _type_: _description_
    """
    return functools.partial(sync_try, exc=exc)  # type: ignore