fix -package:incipit-base -is:module package:data-fix

newtype Fix f
data-fix Data.Fix
A fix-point type.
Fix :: f (Fix f) -> Fix f
data-fix Data.Fix
package data-fix
Uses
Fixpoint data types Fixpoint types and recursion schemes. If you define your AST as fixpoint type, you get fold and unfold operations for free. Thanks for contribution to: Matej Kollar, Herbert Valerio Riedel
foldFix :: Functor f => (f a -> a) -> Fix f -> a
data-fix Data.Fix
Fold Fix. 
>>> let fp = unfoldFix (\i -> if i < 4 then Cons i (i + 1) else Nil) (0 :: Int)

>>> foldFix (elimListF 0 (+)) fp
6
foldFixM :: (Monad m, Traversable t) => (t a -> m a) -> Fix t -> m a
data-fix Data.Fix
Monadic foldFix.
hoistFix :: Functor f => (forall a . f a -> g a) -> Fix f -> Fix g
data-fix Data.Fix
Change base functor in Fix.
hoistFix' :: Functor g => (forall a . f a -> g a) -> Fix f -> Fix g
data-fix Data.Fix
Like hoistFix but fmapping over g.
unFix :: Fix f -> f (Fix f)
data-fix Data.Fix
unfoldFix :: Functor f => (a -> f a) -> a -> Fix f
data-fix Data.Fix
Unfold Fix. 
>>> unfoldFix (\i -> if i < 4 then Cons i (i + 1) else Nil) (0 :: Int)
Fix (Cons 0 (Fix (Cons 1 (Fix (Cons 2 (Fix (Cons 3 (Fix Nil))))))))
unfoldFixM :: (Monad m, Traversable t) => (a -> m (t a)) -> a -> m (Fix t)
data-fix Data.Fix
Monadic anamorphism.
unwrapFix :: Fix f -> f (Fix f)
data-fix Data.Fix
Unwrap Fix. 
>>> let x = unfoldFix (\i -> if i < 3 then Cons i (i + 1) else Nil) (0 :: Int)

>>> unwrapFix x
Cons 0 (Fix (Cons 1 (Fix (Cons 2 (Fix Nil)))))
wrapFix :: f (Fix f) -> Fix f
data-fix Data.Fix
Wrap Fix. 
>>> let x = unfoldFix (\i -> if i < 3 then Cons i (i + 1) else Nil) (0 :: Int)

>>> wrapFix (Cons 10 x)
Fix (Cons 10 (Fix (Cons 0 (Fix (Cons 1 (Fix (Cons 2 (Fix Nil))))))))