Ascii fractals

ascii-fractals.hs

import System.Environment

type Pattern = [[Char]]

fractalize :: Pattern -> Int -> String
fractalize [] _ = ""
fractalize pat k = unlines [ [ charAt k i j | j <- [0..m^k - 1] ] | i <- [0..n^k - 1] ]
  where
    n = length pat
    m = length (head pat)
    charAt 1 i j = pat!!i!!j
    charAt k i j
      | x == '#' = pat!!(i`mod`n)!!(j`mod`m)
      | otherwise = ' '
      where x = charAt (k - 1) (i`div`n) (j`div`m)

pattern1 :: Pattern
pattern1 = [ " # "
           , "###"
           , " # "]

main :: IO ()
main = getK >>= putStr . fractalize pattern1
  where getK = read . head <$> getArgs