difference package:unordered-containers

difference :: (Eq k, Hashable k) => HashMap k v -> HashMap k w -> HashMap k v

unordered-containers Data.HashMap.Internal Data.HashMap.Internal.Strict Data.HashMap.Lazy Data.HashMap.Strict

Difference of two maps. Return elements of the first map not existing in the second.

difference :: (Eq a, Hashable a) => HashSet a -> HashSet a -> HashSet a

unordered-containers Data.HashSet Data.HashSet.Internal

Difference of two sets. Return elements of the first set not existing in the second.

>>> HashSet.difference (HashSet.fromList [1,2,3]) (HashSet.fromList [2,3,4])
fromList [1]

differenceWith :: (Eq k, Hashable k) => (v -> w -> Maybe v) -> HashMap k v -> HashMap k w -> HashMap k v

unordered-containers Data.HashMap.Internal Data.HashMap.Internal.Strict Data.HashMap.Lazy Data.HashMap.Strict

Difference with a combining function. When two equal keys are encountered, the combining function is applied to the values of these keys. If it returns Nothing, the element is discarded (proper set difference). If it returns (Just y), the element is updated with a new value y.