Zygohistomorphic prepromorphisms: Difference between revisions
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Zygohistomorphic prepromorphisms are an intentionally overcomplicated combination of recursion-schemes concepts that started as a joke<ref>[https://archive.ph/2Jlo6] Edward Kmett on Twitter, 2019</ref>. | |||
< | 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. <code>Zygo</code> implements semi-mutual recursion like a zygomorphism. ''Para'' gives you access to your result à la paramorphism. | ||
</ | <haskell> | ||
import Control.Morphism.Zygo | |||
import Control.Morphism.Prepro | |||
import Control.Morphism.Histo | |||
import Control.Functor.Algebra | |||
import Control.Functor.Extras | |||
zygoHistoPrepro | |||
:: (Unfoldable t, Foldable t) | |||
=> (Base t b -> b) | |||
-> (forall c. Base t c -> Base t c) | |||
-> (Base t (EnvT b (Stream (Base t)) a) -> a) | |||
-> t | |||
-> a | |||
zygoHistoPrepro f g t = gprepro (distZygoT f distHisto) g t | |||
-- unless you want a generalized zygomorphism. | |||
</haskell> | |||
<references /> | |||
[[Category:Code]] | |||
[[Category:Language extensions]] | |||
Latest revision as of 15:40, 20 July 2023
Zygohistomorphic prepromorphisms are an intentionally overcomplicated combination of recursion-schemes concepts that started as a joke[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. Zygo implements semi-mutual recursion like a zygomorphism. Para gives you access to your result à la paramorphism.
import Control.Morphism.Zygo
import Control.Morphism.Prepro
import Control.Morphism.Histo
import Control.Functor.Algebra
import Control.Functor.Extras
zygoHistoPrepro
:: (Unfoldable t, Foldable t)
=> (Base t b -> b)
-> (forall c. Base t c -> Base t c)
-> (Base t (EnvT b (Stream (Base t)) a) -> a)
-> t
-> a
zygoHistoPrepro f g t = gprepro (distZygoT f distHisto) g t
-- unless you want a generalized zygomorphism.