Difference between revisions of "Zygohistomorphic prepromorphisms"

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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.
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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.
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<pre>
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import Control.Morphism.Zygo
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import Control.Morphism.Prepro
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import Control.Morphism.Histo
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import Control.Functor.Algebra
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import Control.Functor.Extras
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zygoHistoPrepro
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:: (Unfoldable t, Foldable t)
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=> (Base t b -> b)
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-> (forall c. Base t c -> Base t c)
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-> (Base t (EnvT b (Stream (Base t)) a) -> a)
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-> t
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-> a
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zygoHistoPrepro f g t = gprepro (distZygoT f distHisto) g t
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-- unless you want a generalized zygomorphism.
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</pre>

Latest revision as of 21:03, 20 February 2011

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.