open System.Diagnostics

let fsiProcess =
    let filename,args = if System.Environment.OSVersion.Platform = System.PlatformID.Unix
                        then
                            "/opt/mono-2.10/bin/mono", "/usr/lib/fsharp/fsi.exe"   // does not work
                            // "fsharpi", "" // does not work
                            // "/usr/bin/mono", "/usr/lib/fsharp/fsi.exe" // does not work
                        else
                            @"C:\Program Files (x86)\Microsoft F#\v4.0\fsi.exe", ""
    let startInfo =
      new ProcessStartInfo
        (FileName = filename, UseShellExecute = false, Arguments = args,
         RedirectStandardError = true, CreateNoWindow = true, RedirectStandardOutput = true,
         RedirectStandardInput = true)
    try
      let p = Process.Start(startInfo)
      do p.EnableRaisingEvents <- true
      do p.BeginOutputReadLine ()
      p
    with e ->
      printfn "bah"
      reraise()

fsiProcess.OutputDataReceived.Add(fun x ->
                                    let s = x.Data
                                    printfn "received %s:" s)

fsiProcess.StandardInput.WriteLine ("let foo = 1;;\n")

System.Console.ReadKey () |> ignore

fsiProcess.Kill ()