Data.Set.Lens

Documentation

contains :: Ord k => k -> Simple Lens (Set k) Bool

This Lens can be used to read, write or delete a member of a Set

 ghci> contains 3 +~ False $ Set.fromList [1,2,3,4]
 fromList [1,2,4]

 contains :: Ord k => k -> (Bool -> f Bool) -> Set k -> f (Set k)

members :: (Ord i, Ord j) => Setter (Set i) (Set j) i j

This Setter can be used to change the type of a Set by mapping the elements to new values.

Sadly, you can't create a valid Traversal for a Set, but you can manipulate it by reading using folded and reindexing it via setmap.

 ghci> adjust members (+1) (fromList [1,2,3,4]
 fromList [2,3,4,5]