import SimplePrelude

-- The type of an array:
type Array a = Int -> a

-- Constructors of arrays:
emptyArray :: Array a
emptyArray i = error ("Access to non-initialized index ")

initArray :: a -> Array a
initArray c = const c

putIndex :: Array a -> Int -> a -> Array a
putIndex a i v = a'
 where a' j | j == i    = v
            | otherwise = a j

-- Selector a[i]:
getIndex :: Array a -> Int -> a
getIndex a i = a i

hw = putIndex (putIndex emptyArray 1 "World") 0 "Hello"

hwe = putIndex (putIndex (initArray "") 1 "World") 0 "Hello"