Data.Array.Lens

Indexing

ix :: (IArray a e, Ix i) => i -> Simple Lens (a i e) e

Access an element of an array.

Note: The indexed element is assumed to exist in the target IArray.

arr ! i = arr ^. ix i

arr // [(i,e)] = ix i .~ e $ arr

>>> ix 2 .~ 9 $ (listArray (1,5) [4,5,6,7,8] :: Array Int Int)
array (1,5) [(1,4),(2,9),(3,6),(4,7),(5,8)]

Setters

ixmapped :: (IArray a e, Ix i, Ix j) => (i, i) -> Setter (a j e) (a i e) i j

This setter can be used to derive a new IArray from an old array by applying a function to each of the indices to look it up in the old IArray.

This is a contravariant Setter.

ixmap = over . ixmapped

ixmapped = sets . ixmap

over (ixmapped b) f arr ! i = arr ! f i

bounds (over (ixmapped b) f arr) = b

Traversal

traverseArray :: (IArray a c, IArray a d, Ix i) => IndexedTraversal i (a i c) (a i d) c d

An IndexedTraversal of the elements of an IArray, using the index into the array as the index of the traversal.

amap = over traverseArray