module Data.Accessor.Container
(array, mapDefault, mapMaybe, ) where
import qualified Data.Accessor.Basic as Accessor
import qualified Data.Array as Array
import qualified Data.Map as Map
import Prelude hiding (map)
array :: Array.Ix i => i -> Accessor.T (Array.Array i e) e
array i = Accessor.fromSetGet (\e a -> a Array.// [(i,e)]) (Array.! i)
mapDefault :: Ord key => elem -> key -> Accessor.T (Map.Map key elem) elem
mapDefault deflt key =
Accessor.fromSetGet (Map.insert key) (Map.findWithDefault deflt key)
mapMaybe :: Ord key => key -> Accessor.T (Map.Map key elem) (Maybe elem)
mapMaybe key =
Accessor.fromSetGet
(\e m -> maybe (Map.delete key m) (flip (Map.insert key) m) e)
(Map.lookup key)