# Zygohistomorphic prepromorphisms

Revision as of 15:40, 20 July 2023 by Hécate Moonlight (talk | contribs)

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.
```