Protolude.Either

Documentation

maybeToLeft :: r -> Maybe l -> Either l r

maybeToRight :: l -> Maybe r -> Either l r

leftToMaybe :: Either l r -> Maybe l

rightToMaybe :: Either l r -> Maybe r

maybeEmpty :: Monoid b => (a -> b) -> Maybe a -> b

maybeToEither :: e -> Maybe a -> Either e a

fromLeft :: a -> Either a b -> a

Return the contents of a Left-value or a default value otherwise.

Examples

Basic usage:

>>> fromLeft 1 (Left 3)
3
>>> fromLeft 1 (Right "foo")
1

Since: base-4.10.0.0

fromRight :: b -> Either a b -> b

Return the contents of a Right-value or a default value otherwise.

Examples

Basic usage:

>>> fromRight 1 (Right 3)
3
>>> fromRight 1 (Left "foo")
1

Since: base-4.10.0.0