Zygohistomorphic prepromorphisms

From HaskellWiki
Revision as of 00:44, 10 June 2008 by Roconnor (talk | contribs)
Jump to: navigation, search

Used when you really need both semi-mutual recursion and history and to repeatedly apply a natural transformation as you get deeper into the functor. Zygo implements semi-mutual recursion like a zygomorphism. Para gives you access to your result ala a paramorphism.

import Control.Morphism.Zygo
import Control.Morphism.Prepro
import Control.Morphism.Histo
import Control.Functor.Algebra
import Control.Functor.Extras

zygohistomorphic_prepromorphism :: Functor f => Algebra f b -> GAlgebra f (Cofree f) a -> (f :~> f) -> FixF f -> a
zygohistomorphic_prepromorphism f = g_prepro (distZygoT (liftAlgebra f) (distHisto id))
-- unless you want a generalized zygomorphism.