Data.Functor.Identity

The identity functor and monad.

This trivial type constructor serves two purposes:

• It can be used with functions parameterized by functor or monad classes.
• It can be used as a base monad to which a series of monad transformers may be applied to construct a composite monad. Most monad transformer modules include the special case of applying the transformer to Identity. For example, State s is an abbreviation for StateT s Identity.

Documentation

newtype Identity a

Identity functor and monad. (a non-strict monad)

Constructors

Identity a

Instances

Monad Identity

Functor Identity

MonadFix Identity

Applicative Identity

Foldable Identity

Traversable Identity

Show1 Identity

Read1 Identity

Ord1 Identity

Eq1 Identity

Eq a => Eq (Identity a)

Ord a => Ord (Identity a)

Read a => Read (Identity a)

Show a => Show (Identity a)

runIdentity :: Identity a -> a

Inverse of Identity.