Christmas tree in Haskell

newyear.hs

-- Usage:
--    runhaskell newyear.hs n
-- This will print a nice christmas tree. For n=5:
--
--      *
--     * *
--    * * *
--   * * * *
--  * * * * *
--  Happy New Year!

import Data.List
import System.Environment

spaces total n = take (total-n) (repeat ' ')
stars n = intersperse ' ' $ take n (repeat '*')
line total n = spaces total n ++ stars n

main = do [arg] <- getArgs
          let total = read arg in mapM_ putStrLn (map (line total) [1..total])
          putStrLn "Happy New Year!"