Data.Either.Strict

The strict variant of the standard Haskell Either type and the corresponding variants of the functions from Data.Either.

Note that the strict Either type is not an applicative functor, and therefore also no monad. The reasons are the same as the ones for the strict Maybe type, which are explained in Data.Maybe.Strict.

Documentation

data Either a b :: * -> * -> *

The strict choice type.

Constructors

Left !a

Right !b

Instances

Functor (Either a)

(Eq a, Eq b) => Eq (Either a b)

(Ord a, Ord b) => Ord (Either a b)

(Read a, Read b) => Read (Either a b)

(Show a, Show b) => Show (Either a b)

type Rep (Either a b)

isRight :: Either a b -> Bool

Yields True iff the argument is of the form Right _.

isLeft :: Either a b -> Bool

Yields True iff the argument is of the form Left _.

either :: (a -> c) -> (b -> c) -> Either a b -> c

Case analysis: if the value is Left a, apply the first function to a; if it is Right b, apply the second function to b.

lefts :: [Either a b] -> [a]

Analogous to lefts in Data.Either.

rights :: [Either a b] -> [b]

Analogous to rights in Data.Either.

partitionEithers :: [Either a b] -> ([a], [b])

Analogous to partitionEithers in Data.Either.

_Left :: Prism (Either a c) (Either b c) a b

Analogous to _Left in Control.Lens.Prism.

_Right :: Prism (Either c a) (Either c b) a b

Analogous to _Right in Control.Lens.Prism.