Triangle string with alternating 0 and 1 characters

Triangle2.hs

import           Data.List      (intersperse)
import           Data.Monoid    (mconcat)

triangleIO :: IO ()
triangleIO = putStrLn triangle

triangle :: String
triangle = mconcat . intersperse "\n" . fmap (intersperse ' ') $ cycle ['0']
  where cycle x = x : (cycle x >>= growOne)
        growOne (x:z) = [opp x:x:z]
        opp '0' = '1'
        opp '1' = '0'