How to write to the the beginning of file in F#

Question

I need to write a running number - at the beginning of existing files. All I have been able to do so far is to write to the end of each file. Any help please?

Answer 1

How about (warning! untested code):

open System.IO
File.ReadAllText("c:\\old.txt")
    |> fun s -> let r = new StreamReader(s)
                let data = r.ReadToEnd
                r.Close()
                s.Close()
                data

let writeStringToFile d =
    (File.OpenWrite("c:\\new.txt"), d)
    |> fun ((s : FileStream), (d : string)) -> let r = new StreamWriter(s)
                                               r.WriteLine("new data")
                                               r.Write(d)
                                               r.Close()
                                               s.Close()

getStringFromFile()
|> writeStringToFile

EDIT:

Much better solution:

File.WriteAllText("c:\\new.txt", "new Text" + File.ReadAllText("c:\\old.txt"))