insertWith'

insertWith' :: (a -> a -> a) -> Key -> a -> IntMap a -> IntMap a
containers Data.IntMap
Deprecated. As of version 0.5, replaced by insertWith. O(log n). Same as insertWith, but the result of the combining function is evaluated to WHNF before inserted to the map.
insertWith' :: Ord k => (a -> a -> a) -> k -> a -> Map k a -> Map k a
containers Data.Map
Deprecated. As of version 0.5, replaced by insertWith. O(log n). Same as insertWith, but the value being inserted to the map is evaluated to WHNF beforehand. For example, to update a counter: > insertWith' (+) k 1 m