# Difference between revisions of "Zygohistomorphic prepromorphisms"

From HaskellWiki

m |
|||

Line 1: | Line 1: | ||

− | 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. | + | 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. |

<pre> | <pre> | ||

Line 8: | Line 8: | ||

zygohistomorphic_prepromorphism :: Algebra f b -> GAlgebra f (Cofree f) a -> (f :~> f) -> FixF f -> a | zygohistomorphic_prepromorphism :: 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. | + | zygohistomorphic_prepromorphism f = g_prepro (distZygoT (liftAlgebra f) (distHisto id)) |

+ | -- unless you want a generalized zygomorphism. | ||

</pre> | </pre> |

## Revision as of 01:39, 9 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 zygohistomorphic_prepromorphism :: 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.