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module MonMap where
import qualified Data.Map.Strict as Map
newtype MonMap k v = MonMap (Map.Map k v)
deriving (Show)
instance Functor (MonMap k) where
fmap f (MonMap m) = MonMap (fmap f m)
instance (Ord k, Semigroup v) => Semigroup (MonMap k v) where
MonMap m1 <> MonMap m2 = MonMap (Map.unionWith (<>) m1 m2)
instance (Ord k, Monoid v) => Monoid (MonMap k v) where
mempty = MonMap mempty
singleton :: k -> v -> MonMap k v
singleton = (MonMap .) . Map.singleton
lookup :: Ord k => k -> MonMap k v -> Maybe v
lookup k (MonMap m) = Map.lookup k m
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