[Haskell-cafe] Implementing and indexing 2 dimen arrays

[Alex Gontcharov]

I am writing a function, It's my first Haskell program
in output function
I will be working on [[3,4],[1,2,3,2],[3,9,9,4],[8,3,3,4] type
structures
I'd like to know how to index a particular element at run-time
as I don't know on which element of which sublist I am at the moment
in pullHelper function which starts with values !! ind p xs !! 

in C it would look something like 

values[][10]={{....}.{....}..};
int index[4]={3,4,6,7}; 
int i; i
for(i = 0; i<4; i++) {  
int c = index[i];
  if(values[i][c-1] == 0) 
	/* do something */
  else
	/*other things*/
}
Any help would be appreciated

 --Stack for the digits of numbers, a modulo b,
    stack :: Int->Int->[[Int]]
    stack x y  = reverse (split (subStack x y))
        where
        --Split the digits further and constructs lists of lists
        split :: [Int]->[[Int]]
        split xs
            | length xs == 0 = []
            | otherwise = (reverse (subStack (head xs) 10)):
              (split (tail xs))
        subStack :: Int->Int->[Int]
        subStack x y
            | x == 0 = []
            | otherwise = (mod x y):(subStack (div x y) y)

    -- It should work for 999999999 range but since I am using
    -- Int maximum is 2^31-1
    output :: Int->[Char]
    output n  = loop (stack n 10000)
        where
        -- goes through sets of at most 4 digits in the list, loop 
        loop :: [[Int]]->[Char]
        loop xs
            | length xs == 0 = []
            | otherwise = (strCon (head xs)) : (loop (tail xs))

        strCon :: [Int]->[Char]
        strCon xs
            | length xs == 0 = []
            | otherwise = (pullStr (head xs)) : (strCon (tail xs))

        pullStr :: Int->[Char]
        pullStr s
            | s == 0 = []
            | otherwise = pullHelper s
        --Helping to pull elements from the set, nested if
        pullHelper :: Int->[Char]
        pullHelper p
            | values !! ind p xs !! p - 1 == 0 =
                ones !! p - 1 ++ values !! ind p xs !! 0
            | otherwise = values !! ind p xs !! p - 1
            --Nasty !