Re: [Haskell-cafe] Newbied question on IO Monad

On Tue, 12 Sep 2006, Sara Kenedy wrote:

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.

http://haskell.org/hawiki/ThatAnnoyingIoType