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Define an Applicative instance for Incr.

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Rob Rix 2019-07-02 09:29:35 -04:00
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commit d0f9cbbc10
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5
semantic-core/src/Data/Name.hs
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@ -134,6 +134,11 @@ data Incr a
| S a
deriving (Eq, Foldable, Functor, Ord, Show, Traversable)
instance Applicative Incr where
pure = S
Z <*> _ = Z
S f <*> a = f <$> a
match :: (Applicative f, Eq a) => a -> a -> Incr (f a)
match x y | x == y = Z
| otherwise = S (pure y)