{-# LANGUAGE Rank2Types #-} ----------------------------------------------------------------------------- -- | -- Module : Data.Array.Lens -- Copyright : (C) 2012-14 Edward Kmett -- License : BSD-style (see the file LICENSE) -- Maintainer : Edward Kmett <ekmett@gmail.com> -- Stability : provisional -- Portability : MPTCs, Rank2Types, LiberalTypeSynonyms -- ---------------------------------------------------------------------------- module Data.Array.Lens ( -- * Setters ixmapped ) where import Control.Lens import Data.Array.IArray hiding (index) -- | 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'. -- -- @ -- 'ixmap' ≡ 'over' '.' 'ixmapped' -- 'ixmapped' ≡ 'setting' '.' 'ixmap' -- 'over' ('ixmapped' b) f arr '!' i ≡ arr '!' f i -- 'bounds' ('over' ('ixmapped' b) f arr) ≡ b -- @ ixmapped :: (IArray a e, Ix i, Ix j) => (i,i) -> IndexPreservingSetter (a j e) (a i e) i j ixmapped = setting . ixmap {-# INLINE ixmapped #-}