Hi, Could someone please tell me how to check this program. The problem is where do I find the output? I laod this into ghc and it comes up OK modules loaded: Main gchi> How do I now check if it works or see the result. Program below (taken from real world haskell) -- file: ch07/toupper-imp.hs import System.IO import Data.Char(toUpper) main :: IO () main = do inh <- openFile "quux.txt" ReadMode outh <- openFile "output.txt" WriteMode mainloop inh outh hClose inh hClose outh mainloop :: Handle -> Handle -> IO () mainloop inh outh = do ineof <- hIsEOF inh if ineof then return () else do inpStr <- hGetLine inh hPutStrLn outh (map toUpper inpStr) mainloop inh outh John