lens-3.8.7.3: Lenses, Folds and Traversals

Portability | portable
Stability | provisional
Maintainer | Edward Kmett <ekmett@gmail.com>
Safe Haskell | None

Data.IntSet.Lens

Description

Synopsis

- members :: Fold IntSet Int
- setmapped :: IndexPreservingSetter' IntSet Int
- setOf :: Getting IntSet s t Int b -> s -> IntSet

# Documentation

members :: Fold IntSet Int

IntSet isn't Foldable, but this `Fold` can be used to access the members of an `IntSet`.

    >>> sumOf members $ setOf folded [1,2,3,4]
    10

setmapped :: IndexPreservingSetter' IntSet Int

This `Setter` can be used to change the contents of an `IntSet` by mapping the elements to new values.

Sadly, you can't create a valid `Traversal` for a `Set`, because the number of elements might change but you can manipulate it by reading using `folded` and reindexing it via `setmapped`.

    >>> over setmapped (+1) (fromList [1,2,3,4])
    fromList [2,3,4,5]

setOf :: Getting IntSet s t Int b -> s -> IntSet

Construct an `IntSet` from a `Getter`, `Fold`, `Traversal`, `Lens` or `Iso`.

    >>> setOf folded [1,2,3,4]
    fromList [1,2,3,4]

    >>> setOf (folded._2) [("hello",1),("world",2),("!!!",3)]
    fromList [1,2,3]

     setOf :: Getter s Int     -> s -> IntSet
     setOf :: Fold s Int       -> s -> IntSet
     setOf :: Iso' s Int       -> s -> IntSet
     setOf :: Lens' s Int      -> s -> IntSet
     setOf :: Traversal' s Int -> s -> IntSet