W3cubDocs

/Haskell 7

Data.Functor.Identity

Copyright (c) Andy Gill 2001, (c) Oregon Graduate Institute of Science and Technology 2001
License BSD-style (see the file LICENSE)
Maintainer [email protected]
Stability experimental
Portability portable
Safe Haskell Trustworthy
Language Haskell2010

Description

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.

Since: 4.8.0.0

newtype Identity a Source

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

Since: 4.8.0.0

Constructors

Identity

Fields

runIdentity :: a

Instances

Monad Identity
Functor Identity
MonadFix Identity
Applicative Identity
Foldable Identity
Traversable Identity
Generic1 Identity
MonadZip Identity
Eq a => Eq (Identity a)
Data a => Data (Identity a)
Ord a => Ord (Identity a)
Read a => Read (Identity a)

This instance would be equivalent to the derived instances of the Identity newtype if the runIdentity field were removed
Show a => Show (Identity a)

This instance would be equivalent to the derived instances of the Identity newtype if the runIdentity field were removed
Generic (Identity a)
type Rep1 Identity
type Rep (Identity a)

© The University of Glasgow and others
Licensed under a BSD-style license (see top of the page).
https://downloads.haskell.org/~ghc/7.10.3/docs/html/libraries/base-4.8.2.0/Data-Functor-Identity.html