lens-1.1: Families of Lenses, Folds and Traversals
Data.Set.Lens
Description
Synopsis
contains :: Ord k => k -> Simple Lens (Set k) BoolSource
This Lens can be used to read, write or delete a member of a Set
Lens
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)