如何使用在一个函数内另一个函数内创建的变量？ F＃

Question

我试图使我的服务器/客户端聊天更像一个p2p应用，其中一个使用开始作为主机，另一个使用连接，然后成为主机，原始主机也作为客户端连接到他。但是我无法使用connectedStream中tryListen()中的receive()之类的变量。如果我不得不猜测这是不可能的，那么我必须以某种方式进行重组，但我想以防万一。完整代码如下。

open System
open System.Net
open System.Net.Sockets
open System.Text
open System.Threading

printf "Connect from IP: "; let connectFromIP = Console.ReadLine() |> IPAddress.Parse;;
printf "Connect from Port: "; let connectFromPort = Console.ReadLine() |> int;;

printf "Connect to IP: "; let connectToIP = Console.ReadLine();;
printf "Connect to Port: "; let connectToPort = Console.ReadLine() |> int;;

let buffer: byte[] = Array.zeroCreate 256

let rec tryListen() =
    try
        let tcpListener = new TcpListener(connectFromIP, connectFromPort)
        tcpListener.Start()
        printfn "Waiting for Client."
        let connectedClient = tcpListener.AcceptTcpClient()
        let connectedStream = connectedClient.GetStream()
        printfn "Client connected."
    with
        | _ ->
            printfn "Retrying..."
            Thread.Sleep(1000)
            tryListen()

let rec tryConnect() =
    try
        let tcpClient = new TcpClient(connectToIP, connectToPort)
        let clientStream = tcpClient.GetStream()
        printfn "Connected to Server."
    with
        | _ ->
            printfn "Retrying..."
            Thread.Sleep(1000)
            tryConnect()

printfn "Listen or Connect first? (L/C)"; let choice = Console.ReadLine();;

match choice with
| "L" | "l" -> tryListen()
| "C" | "c" -> tryConnect()
| _ -> ()

let rec chat() =
    let receive() = async {
        let connectStreamReader = connectedStream.Read(buffer, 0, buffer.Length)
        let data = Encoding.ASCII.GetString(buffer, 0, connectStreamReader)
        printfn "Received: %s" data
        connectedStream.Flush()
        chat()
    }

    let send() = async {
        printfn "Message: "
        let message: byte[] = Encoding.ASCII.GetBytes(Console.ReadLine())
        clientStream.Write(message, 0, message.Length)
        clientStream.Flush()
        send() |> ignore
    }

    [ receive(); send() ]
    |> Async.Parallel
    |> Async.RunSynchronously
    |> ignore

chat()