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Define Foldable instances for Unions.

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Rob Rix 2017-04-06 14:16:10 -04:00
parent 68724970d0
commit b0700242ee
1 changed files with 8 additions and 0 deletions
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8
src/Data/Functor/Union.hs
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@ -44,6 +44,14 @@ instance {-# OVERLAPPABLE #-} InUnion fs f => InUnion (g ': fs) f where
proj _ = Nothing
instance (Foldable f, Foldable (Union fs)) => Foldable (Union (f ': fs)) where
foldMap f (Here r) = foldMap f r
foldMap f (There t) = foldMap f t
instance Foldable (Union '[]) where
foldMap _ _ = mempty
instance (Eq (f a), Eq (Union fs a)) => Eq (Union (f ': fs) a) where
Here f1 == Here f2 = f1 == f2
There fs1 == There fs2 = fs1 == fs2