category-extras-0.53.0: Various modules and constructs inspired by category theory Source code Contents Index

Control.Comonad.Reader Portability portable Stability experimental Maintainer Edward Kmett <ekmett@gmail.com>

Description

If you look at the reader arrow: (e, a) -> a you can see that all the interesting bits are bunched on the left. This is that comonad. Flipping the pair and currying the arguments yields a -> (e -> a), and you can recognize the (e -> a) as the reader monad. In more technical language the Reader comonad is left adjoint to the Reader monad.

Documentation

data Coreader r a Source

Constructors Coreader r a Instances QFunctor Coreader Hask Hask PFunctor Coreader Hask Hask Bifunctor Coreader Hask Hask Hask ComonadReader r (Coreader r) Functor (Coreader r) Copointed (Coreader r) Comonad (Coreader r) Zap (Reader e) (Coreader e) Adjunction (Coreader e) (Reader e) Representable (Reader e) (Coreader e ())

runCoreader :: Coreader r a -> (r, a) Source

newtype CoreaderT w r a Source

Constructors CoreaderT runCoreaderT :: w (r, a) Instances Comonad w => ComonadReader r (CoreaderT w r) ComonadCofree f w => ComonadCofree f (CoreaderT w e) Functor f => QFunctor (CoreaderT f) Hask Hask Functor f => PFunctor (CoreaderT f) Hask Hask Functor f => Bifunctor (CoreaderT f) Hask Hask Hask Functor f => Functor (CoreaderT f b) Copointed w => Copointed (CoreaderT w b) Comonad w => Comonad (CoreaderT w b)

class Comonad w => ComonadReader r w | w -> r where Source

Methods askC :: w a -> r Source Instances ComonadReader e ((,) e) ComonadReader r (Coreader r) ComonadReader e w => ComonadReader e (Density w) ComonadReader e m => ComonadReader e (CoYoneda m) ComonadReader e m => ComonadReader e (Yoneda m) Comonad w => ComonadReader r (CoreaderT w r)

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