Rx Spawn Child Process

RxSpawnChildProcess.fs

    
    let tryDontCare f =
        try 
            f()
        with | _ -> ()

    let observableFromProcess program args = 
        Observable.Create(fun (obs : IObserver<string>) -> 
            let pInfo = ProcessStartInfo(program,args)
            pInfo.RedirectStandardOutput <- true
            pInfo.RedirectStandardError <- true
            pInfo.UseShellExecute <- false
            let shellProcess = Process.Start(pInfo)
            shellProcess.BeginOutputReadLine()
            shellProcess.BeginErrorReadLine()
            let exitSub = shellProcess.Exited
                            |> Observable.map(fun _ -> shellProcess.ExitCode)
                            |> Observable.filter(fun exitCode -> exitCode <> 0)
                            |> Observable.map(fun exitCode -> new Exception(sprintf "Process exited with %d" exitCode))
                            |> Observable.subscribe(obs.OnError) 
            let dataFeed = 
                shellProcess.OutputDataReceived
                 |> Observable.map(fun x -> x.Data)
                 |> Observable.subscribe(obs.OnNext)
            //WARNING: Sometimes errors aren't really "errors", people just like red text for warnings
            //May be better to use a discriminated union and have the subscriber determine what to do
            //            let errorFeed = 
            //                shellProcess.ErrorDataReceived
            //                |> Observable.map (fun x -> Exception(x.Data))
            //                |> Observable.subscribe (obs.OnError)
            Action(fun () ->                              
                shellProcess.CancelOutputRead |> tryDontCare
                dataFeed.Dispose |> tryDontCare
                exitSub.Dispose |> tryDontCare
                shellProcess.Kill |> tryDontCare
                shellProcess.Dispose |> tryDontCare
                ))