lens-3.9.2: Lenses, Folds and Traversals

PortabilityMPTCs, Rank2Types, LiberalTypeSynonyms
Stabilityprovisional
MaintainerEdward Kmett <ekmett@gmail.com>
Safe HaskellNone

Data.Array.Lens

Contents

Description

 

Synopsis

Setters

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

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

This is a contravariant Setter.

 ixmapover . ixmapped
 ixmappedsetting . ixmap
 over (ixmapped b) f arr ! i ≡ arr ! f i
 bounds (over (ixmapped b) f arr) ≡ b