lens-1.3: Lenses, Folds and Traversals

MaintainerEdward Kmett <ekmett@gmail.com>
Safe HaskellSafe-Infered






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

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 jSource

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]

setOf :: Getting (Set c) a b c d -> a -> Set cSource

Construct a set from a Getter, Fold, Traversal, Lens or Iso.

 setOf ::          Getter a c        -> a -> Set c
 setOf :: Ord c => Fold a c          -> a -> Set c
 setOf ::          Iso a b c d       -> a -> Set c
 setOf ::          Lens a b c d      -> a -> Set c
 setOf :: Ord c => Traversal a b c d -> a -> Set c