Prelude.Source.Data.Either

Documentation

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

The Either type represents values with two possibilities: a value of type Either a b is either Left a or Right b.

The Either type is sometimes used to represent a value which is either correct or an error; by convention, the Left constructor is used to hold an error value and the Right constructor is used to hold a correct value (mnemonic: "right" also means "correct").

Constructors

Left a

Right b

Instances

Monad (Either e)

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)

Typeable (* -> * -> *) Either

type (==) (Either k k1) a b = EqEither k k1 a b

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

Case analysis for the Either type. If the value is Left a, apply the first function to a; if it is Right b, apply the second function to b.