Copyright	(C) 2008-2013 Edward Kmett
License	BSD-style (see the file LICENSE)
Maintainer	Edward Kmett <ekmett@gmail.com>
Stability	provisional
Portability	MPTCs, fundeps
Safe Haskell	Safe
Language	Haskell2010

Control.Comonad.Trans.Cofree

Description

The cofree comonad transformer

Synopsis

Documentation

newtype CofreeT f w a Source

This is a cofree comonad of some functor f, with a comonad w threaded through it at each level.

Constructors

CofreeT
Fields runCofreeT :: w (CofreeF f a (CofreeT f w a))

Instances

(Functor f, Comonad w) => ComonadCofree f (CofreeT f w) Source
Functor f => ComonadTrans (CofreeT f) Source
Alternative f => MonadTrans (CofreeT f) Source
(Alternative f, Monad w) => Monad (CofreeT f w) Source
(Functor f, Functor w) => Functor (CofreeT f w) Source
(Alternative f, Applicative w) => Applicative (CofreeT f w) Source
(Foldable f, Foldable w) => Foldable (CofreeT f w) Source
(Traversable f, Traversable w) => Traversable (CofreeT f w) Source
(Alternative f, MonadZip f, MonadZip m) => MonadZip (CofreeT f m) Source
(Functor f, Comonad w) => Comonad (CofreeT f w) Source
Eq (w (CofreeF f a (CofreeT f w a))) => Eq (CofreeT f w a) Source
(Typeable (* -> ) f, Typeable ( -> ) w, Typeable a, Data (w (CofreeF f a (CofreeT f w a))), Data a) => Data (CofreeT f w a) Source
Ord (w (CofreeF f a (CofreeT f w a))) => Ord (CofreeT f w a) Source
Read (w (CofreeF f a (CofreeT f w a))) => Read (CofreeT f w a) Source
Show (w (CofreeF f a (CofreeT f w a))) => Show (CofreeT f w a) Source

The cofree Comonad of a functor f.

Wrap another layer around a cofree comonad value.

cofree is a right inverse of runCofree.

runCofree . cofree == id

Unpeel the first layer off a cofree comonad value.

runCofree is a right inverse of cofree.

cofree . runCofree == id

This is the base functor of the cofree comonad transformer.

Constructors

a :< (f b) infixr 5

Instances

Functor f => Bifunctor (CofreeF f) Source
Traversable f => Bitraversable (CofreeF f) Source
Foldable f => Bifoldable (CofreeF f) Source
Functor f => Functor (CofreeF f a) Source
Foldable f => Foldable (CofreeF f a) Source
Traversable f => Traversable (CofreeF f a) Source
(Eq a, Eq (f b)) => Eq (CofreeF f a b) Source
(Typeable (* -> ) f, Typeable a, Typeable * b, Data a, Data (f b), Data b) => Data (CofreeF f a b) Source
(Ord a, Ord (f b)) => Ord (CofreeF f a b) Source
(Read a, Read (f b)) => Read (CofreeF f a b) Source
(Show a, Show (f b)) => Show (CofreeF f a b) Source

class (Functor f, Comonad w) => ComonadCofree f w | w -> f where Source

Allows you to peel a layer off a cofree comonad.

Methods

unwrap :: w a -> f (w a) Source

Remove a layer.

Instances

ComonadCofree Maybe NonEmpty Source
ComonadCofree f w => ComonadCofree f (IdentityT w) Source
Functor f => ComonadCofree f (Cofree f) Source
Comonad w => ComonadCofree Identity (CoiterT w) Source
(ComonadCofree f w, Semigroup m, Monoid m) => ComonadCofree f (TracedT m w) Source
ComonadCofree f w => ComonadCofree f (StoreT s w) Source
ComonadCofree f w => ComonadCofree f (EnvT e w) Source
(Functor f, Comonad w) => ComonadCofree f (CofreeT f w) Source
ComonadCofree (Const b) ((,) b) Source

Extract the head of the base functor

Extract the tails of the base functor

coiterT :: (Functor f, Comonad w) => (w a -> f (w a)) -> w a -> CofreeT f w a Source

Unfold a CofreeT comonad transformer from a coalgebra and an initial comonad.