The Cat in the Haskell

cat.hs

import Control.Monad as Monad
import System.Exit
import System.IO as IO
import System.Environment as Env

main :: IO ()
main = do
    -- Get the command line arguments
    args <- Env.getArgs

    -- If we have arguments, read them as files and output them
    if (length args > 0) then catFileArray args

    -- Otherwise, output stdin to stdout
    else catHandle stdin

catFileArray :: [FilePath] -> IO ()
catFileArray = Monad.mapM_ catFile

catFile :: FilePath -> IO ()
catFile f = openFile f ReadMode >>= catHandle

catHandle :: Handle -> IO ()
catHandle h = hGetContents h >>= putStr

http://stackoverflow.com/questions/11475006/how-do-i-implement-cat-in-haskell/11475445#11475445