Il Tue, Sep 12, 2006 at 09:00:19AM -0400, Sara Kenedy ebbe a scrivere:
Hello,
Maybe what I talk is not clear.
I want to take the input string sss of "update" to use in: writeFile "myFile.txt" sss of function "main" and get the value zzz from "main" to assign for the value return of "update". I think I need to change the way to declare two functions to get what I want, but I do not know how.
update :: String -> String update sss = zzz
main = do writeFile "myFile.txt" sss x <- callSystem "myFile.txt" y <- openFile "result.txt" ReadMode zzz <- hGetContents y return zzz
S.
this is what you are trying to do with this code: 1. open a file and write to it an undefined string called "sss" 2. binding x with the value of a function name callSystem that takes a string (we do not know what it returns because it's undefined in this piece of code, but it must be a string). 3. open a file, "result.txt", read its content and put it in the IO Monad. Instead you would like to insert into the file myFile.txt a string, sss, that is the result of applying a function to the content of "result.txt". Am I right? If yes, here some code: update :: String -> String update sss = "This is the content of result.txt:\n" ++ sss main = do y <- openFile "result.txt" ReadMode zzz <- hGetContents y writeFile "myFile.txt" $ update zzz putStrLn "Done!" return () Ciao Andrea