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GMergeable has a gmerge method generalizing gsequenceAlt.

This commit is contained in:
Rob Rix 2016-07-22 17:49:07 -04:00
parent 9ae7f52e8f
commit 1d7645cafe
2 changed files with 13 additions and 13 deletions

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@ -15,4 +15,4 @@ class Functor t => Mergeable t where
-- Instances
instance Mergeable [] where sequenceAlt = gsequenceAlt
instance Mergeable [] where sequenceAlt = gmerge identity

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@ -7,36 +7,36 @@ import Prologue
-- Classes
class GMergeable t where
gsequenceAlt :: Alternative f => t (f a) -> f (t a)
gmerge :: Alternative f => (a -> f b) -> t a -> f (t b)
genericSequenceAlt :: (Generic1 t, GMergeable (Rep1 t), Alternative f) => t (f a) -> f (t a)
genericSequenceAlt = fmap to1 . gsequenceAlt . from1
genericSequenceAlt = fmap to1 . gmerge identity . from1
-- Instances
instance GMergeable U1 where
gsequenceAlt _ = pure U1
gmerge _ _ = pure U1
instance GMergeable Par1 where
gsequenceAlt (Par1 a) = Par1 <$> a
gmerge f (Par1 a) = Par1 <$> f a
instance GMergeable (K1 i c) where
gsequenceAlt (K1 a) = pure (K1 a)
gmerge _ (K1 a) = pure (K1 a)
instance GMergeable f => GMergeable (Rec1 f) where
gsequenceAlt (Rec1 a) = Rec1 <$> gsequenceAlt a
gmerge f (Rec1 a) = Rec1 <$> gmerge f a
instance GMergeable f => GMergeable (M1 i c f) where
gsequenceAlt (M1 a) = M1 <$> gsequenceAlt a
gmerge f (M1 a) = M1 <$> gmerge f a
instance (GMergeable f, GMergeable g) => GMergeable (f :+: g) where
gsequenceAlt (L1 a) = L1 <$> gsequenceAlt a
gsequenceAlt (R1 b) = R1 <$> gsequenceAlt b
gmerge f (L1 a) = L1 <$> gmerge f a
gmerge f (R1 b) = R1 <$> gmerge f b
instance (GMergeable f, GMergeable g) => GMergeable (f :*: g) where
gsequenceAlt (a :*: b) = (:*:) <$> gsequenceAlt a <*> gsequenceAlt b
gmerge f (a :*: b) = (:*:) <$> gmerge f a <*> gmerge f b
instance GMergeable [] where
gsequenceAlt (x:xs) = ((:) <$> x <|> pure identity) <*> gsequenceAlt xs
gsequenceAlt [] = pure []
gmerge f (x:xs) = ((:) <$> f x <|> pure identity) <*> gmerge f xs
gmerge _ [] = pure []