IO example from Haskell.org IO tutorial (http://www.haskell.org/tutorial/io.html)

ioexample.hs

-- IO example from http://www.haskell.org/tutorial/io.html
-- copies one file to another:
main = do fromHandle <- getAndOpenFile "Copy from: " ReadMode
          toHandle   <- getAndOpenFile "Copy to: " WriteMode 
          contents   <- hGetContents fromHandle
          hPutStr toHandle contents
          hClose toHandle
          putStr "Done."