Sierpinski Triangle

Main.hs

module Main where

import Data.List
import Lib

pad :: Int -> [Char] -> [Char]
pad size str
  | length str < size  = str ++ replicate (size - length str) ' '
  | otherwise          = str

duplicate :: Int -> [[Char]] -> [[Char]]
duplicate size triangle =
  let paddedTriangle = map (pad size) triangle
  in
  zipWith (++) paddedTriangle triangle

getSierpinski :: Int -> [[Char]]
getSierpinski 1 = ["*"]
getSierpinski size =
  child ++ (duplicate childSize child)
  where
    childSize = size `div` 2
    child = getSierpinski childSize

drawSierpinski :: Int -> [Char]
drawSierpinski 0 = "*\n"
drawSierpinski size =
  (intercalate "\n" $ getSierpinski size)

main :: IO ()
main =
  let sizes = take 8 $ iterate (*2) 1
  in
  putStr $ foldl1 (++) $ map ((++ "\n\n") . drawSierpinski) sizes