balancedSmileys.hs

module Main where
import System.IO
import System.Environment (getArgs)

balancedSmileys ('(':xs) count   = balancedSmileys xs (count + 1)
balancedSmileys (')':xs) count   = (count > 0) && (balancedSmileys xs (count - 1))
balancedSmileys (':':x:xs) count = if (x == '(') || (x == ')')
                                   then (balancedSmileys xs count) || (balancedSmileys (x:xs) count)
                                   else (balancedSmileys (x:xs) count)
balancedSmileys (x:xs) count     = balancedSmileys xs count  
balancedSmileys [] count         = count == 0

balancedSmileysWrapper xs =
  case (balancedSmileys xs 0) of
    True  -> "YES"
    False -> "NO"  

main :: IO ()
main = do
  args <- getArgs
  handle <- openFile (head args) ReadMode
  contents <- hGetContents handle
  mapM_ (putStrLn . balancedSmileysWrapper) (lines contents)
  hClose handle