|Maintainer||John Goerzen <firstname.lastname@example.org>|
Utilities for working with the Either data type
Copyright (c) 2004 John Goerzen, email@example.com
|:: MonadError e m|
(Left e) will be returned if the Maybe value is Nothing
|-> Maybe a|
(Right a) will be returned if this is (Just a)
|-> m a|
Converts a Maybe value to an Either value, using the supplied parameter as the Left value if the Maybe is Nothing.
This function can be interpreted as:
maybeToEither :: e -> Maybe a -> Either e a
Its definition is given as it is so that it can be used in the Error and related monads.
forceEither, but can raise a specific message with the error.
Takes an either and transforms it into something of the more generic MonadError class.