module Tool.Array (
      Array
    , (!)
    , clear
    , malloc
  ) where

import Data.Vector (Vector, (!?), (//))
import qualified Data.Vector as Vector (replicate)

type Array a = Vector (Maybe a)

(!) :: Array a -> Int -> Maybe a
t ! k =
  case t !? k of
    Nothing -> Nothing
    Just a -> a

clear :: Array a -> Int -> Array a
clear t k = t // [(k, Nothing)]

malloc :: Int -> Array a
malloc size = Vector.replicate size Nothing