Control.Monad.Either

Incompatible with Control.Monad.Error, but removes the Error restriction that prevents a natural encoding of Apomorphisms. This module is therefore incompatible with Control.Monad.Error

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

Typeable2 Either

Coassociative Hask Either

Associative Hask Either

Symmetric Hask Either

Braided Hask Either

Bizap Either (,)

Bizap (,) Either

PreCoCartesian Hask Either

QFunctor Either Hask Hask

PFunctor Either Hask Hask

Distributive Hask (,) Either

Bifunctor Either Hask Hask Hask

Monad (Either e)

Functor (Either a)

MonadFix (Either e)

Applicative (Either e)

Monoid a => HasLimit (Either a)

Pointed (Either a)

Cozip (Either c)

Monoid a => Zip (Either a)

CFunctor (Either a) Hask Hask

(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)

Representable (EitherF a b) (Either a b)

newtype EitherT a m b

Constructors

EitherT

Fields

runEitherT :: m (Either a b)

Instances

Monad m => Monad (EitherT a m)

Functor f => Functor (EitherT a f)

MonadFix m => MonadFix (EitherT a m)

Pointed f => Pointed (EitherT a f)