Need help regarding Async and fsi

Question

I\'d like to write some code that runs a sequence of F# scripts (.fsx). The thing is that I could have literally hundreds of scripts and if I do that:

let sh         


        

Answer 1

In response to Tomas's answer, would this be a workable solution to the race condition involved in starting the process, and then subscribing to its Exited event?

type Process with
    static member AsyncStart psi =
        let proc = new Process(StartInfo = psi, EnableRaisingEvents = true)
        let asyncExit = Async.AwaitEvent proc.Exited
        async {
            proc.Start() |> ignore
            let! args = asyncExit
            return proc
        }

Unless I'm mistaken, this would subscribe to the event prior to starting the process, and package it all up as an Async result.

This would allow you to rewrite the rest of the code like this:

let shellExecute program args = 
  // Configure process to redirect output (so that we can read it)
  let startInfo = 
    new ProcessStartInfo(FileName = program, Arguments = args, 
        UseShellExecute = false,
        WindowStyle = ProcessWindowStyle.Hidden, 
        RedirectStandardOutput = true)

  // Start the process
  Process.AsyncStart(startInfo)

let fsi = "PATH TO FSI.EXE"

let rec loop scripts = async { 
    match scripts with 
    | [] -> printf "FINISHED"
    | script::scripts ->
        // Start the proces in background
        use! p = shellExecute fsi script 
        // Read the output produced by the process, the exit code
        // is available in the `ExitCode` property of `Process`
        let output = p.StandardOutput.ReadToEnd()
        printfn "\nPROCESSED: %s, CODE: %d\n%A" script p.ExitCode output
        // Process the rest of the scripts
        return! loop scripts 
} 

If that does the job, it's certainly a lot less code to worry about than Vladimir's Async.GetSubject.