[Haskell-cafe] Newbied question on IO Monad

[Sara Kenedy]

Hello all,

update :: String -> String
update sss = ...


main = do writeFile "myFile.txt" sss
                x <- callSystem "myFile.txt"
                y <- openFile "result.txt" ReadMode
                zzz <- hGetContents y
                return zzz


I know that function main returns IO String, function update returns
String. And my purpose is to get the string zzz from main for the
value return of function update. But I do not know which way I can do.

Sorry if the question seems ridiculous. Thanks for any help.

S.