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Simplify the type of 'adi'

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This commit is contained in:
John Wiegley 2018-04-20 12:31:46 -07:00
parent 986a3043da
commit e68e369de2
1 changed files with 2 additions and 7 deletions
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9
src/Nix/Utils.hs
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@ -70,16 +70,11 @@ transport f (Fix x) = Fix $ fmap (transport f) (f x)
-- Essentially, it does for evaluation what recursion schemes do for
-- representation: allows threading layers through existing structure, only
-- in this case through behavior.
adi :: Traversable t
=> (t a -> a)
-> ((Fix t -> a) -> Fix t -> a)
-> Fix t -> a
adi :: Functor f => (f a -> a) -> ((Fix f -> a) -> Fix f -> a) -> Fix f -> a
adi f g = g (f . fmap (adi f g) . unFix)
adiM :: (Traversable t, Monad m)
=> (t a -> m a)
-> ((Fix t -> m a) -> Fix t -> m a)
-> Fix t -> m a
=> (t a -> m a) -> ((Fix t -> m a) -> Fix t -> m a) -> Fix t -> m a
adiM f g = g ((f <=< traverse (adiM f g)) . unFix)
type MonoLens a b = forall f. Functor f => (b -> f b) -> a -> f a