On Tue, 10 Oct 2000, Graeme Turner wrote:
Hello,
I am e-mailing you to see if you could offer me a bit of assistance. I have chosen to use Haskell in a minor assignment at my University, Heriot Watt in Edinburgh. The basic aim is to read in a file of data, sort it and then display it.
I have managed to get a sort to function properly but I am having trouble with reading in the data from the file. I have managed to use the hGetContents and hGetLine methods of the IO library to read the data in but when it is read in, it is stored as an IO String type.
I would like to convert the input from the file into one large string so I can process it before sorting it.
Aha, you want to use readFile :: String -> IO String.
After reading the whole file into a variable, how do I then convert that IO String to a String?
You use '<-' in the do notation. readFile "myfile.txt" -- here you have an IO String do contents <- readFile "myfile.txt" return (lines contents) -- here you "convert" the IO String (readFile "myfile.txt") to a String -- (contents). Finally my example returns a list of the lines in the file. I hope this helps. /Lars L