kan-extensions-3.5: Kan extensions, Kan lifts, various forms of the Yoneda lemma, and (co)density (co)monads

PortabilityGADTs, TFs, MPTCs
Stabilityprovisional
MaintainerEdward Kmett <ekmett@gmail.com>
Safe HaskellTrustworthy

Data.Functor.Contravariant.Yoneda.Reduction

Description

Yoneda Reduction of presheafs

http://ncatlab.org/nlab/show/Yoneda+reduction

Synopsis

Documentation

data Yoneda f a whereSource

A Contravariant functor (aka presheaf) suitable for Yoneda reduction.

Constructors

Yoneda :: (a -> b) -> f b -> Yoneda f a 

liftYoneda :: f a -> Yoneda f aSource

Yoneda expansion of a presheaf

lowerYoneda :: Contravariant f => Yoneda f a -> f aSource

Yoneda reduction on a presheaf