Copyright	(C) 2011 Edward Kmett
License	BSD-style (see the file LICENSE)
Maintainer	Edward Kmett <ekmett@gmail.com>
Stability	provisional
Portability	MPTCs, fundeps
Safe Haskell	Safe
Language	Haskell98

Control.Monad.Trans.Contravariant.Adjoint

Description

Uses a contravariant adjunction:

f -| g : Hask^op -> Hask

to build a Comonad to Monad transformer. Sadly, the dual construction, which builds a Comonad out of a Monad, is uninhabited, because any Adjunction of the form

f -| g : Hask -> Hask^op

would trivially admit unsafePerformIO.

Documentation

type Adjoint f g = AdjointT f g Identity #

runAdjoint :: Contravariant g => Adjoint f g a -> g (f a) #

adjoint :: Contravariant g => g (f a) -> Adjoint f g a #

newtype AdjointT f g w a #

Constructors

AdjointT
Fields runAdjointT :: g (w (f a))

Instances

(Adjunction f g, Comonad w) => Monad (AdjointT f g w) #
Methods (>>=) :: AdjointT f g w a -> (a -> AdjointT f g w b) -> AdjointT f g w b # (>>) :: AdjointT f g w a -> AdjointT f g w b -> AdjointT f g w b # return :: a -> AdjointT f g w a # fail :: String -> AdjointT f g w a #
(Adjunction f g, Functor w) => Functor (AdjointT f g w) #
Methods fmap :: (a -> b) -> AdjointT f g w a -> AdjointT f g w b # (<$) :: a -> AdjointT f g w b -> AdjointT f g w a #
(Adjunction f g, Comonad w) => Applicative (AdjointT f g w) #
Methods pure :: a -> AdjointT f g w a # (<>) :: AdjointT f g w (a -> b) -> AdjointT f g w a -> AdjointT f g w b # (>) :: AdjointT f g w a -> AdjointT f g w b -> AdjointT f g w b # (<*) :: AdjointT f g w a -> AdjointT f g w b -> AdjointT f g w a #