Control.Comonad.Contra

Use a contravariant dual adjunction from Hask^op to build a Monad to Comonad transformer.

Documentation

type Contra f g = ContraT f g Identity

runContra :: Contravariant f => Contra f g a -> f (g a)

contra :: Contravariant f => f (g a) -> Contra f g a

newtype ContraT f g m a

Constructors

ContraT

Fields

runContraT :: f (m (g a))

Instances

(Contravariant f, Contravariant g, Monad m) => Functor (ContraT f g m)

(DualAdjunction f g, Monad m) => Comonad (ContraT f g m)