Difference between revisions of "Zygohistomorphic prepromorphisms"
From HaskellWiki
| Line 8: | Line 8: | ||
import Control.Functor.Extras | import Control.Functor.Extras | ||
| − | zygohistomorphic_prepromorphism :: Algebra f b -> GAlgebra f (Cofree f) a -> (f :~> f) -> FixF f -> a | + | 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)) | zygohistomorphic_prepromorphism f = g_prepro (distZygoT (liftAlgebra f) (distHisto id)) | ||
-- unless you want a generalized zygomorphism. | -- unless you want a generalized zygomorphism. | ||
</pre> | </pre> | ||
Revision as of 00:44, 10 June 2008
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.