WebSocketClient.fs

module WebSocketClient

open System
open System.Net.WebSockets
open System.Text
open System.Threading
open Newtonsoft.Json

[<EntryPoint>]
let main argv =

    use cts = new CancellationTokenSource()
    use socket = new ClientWebSocket()

    Async.AwaitTask(socket.ConnectAsync(Uri("wss://mysocketurl"), cts.Token)) |> Async.RunSynchronously

    Logger.log.Information("Connected to socket.")

    let buffer : byte array = Array.zeroCreate 1024
    let segment = ArraySegment(buffer)

    let rec loop() = 
        async {
            Logger.log.Verbose("waiting for message.  Socket state: {0}", socket.State)

            let! result = Async.AwaitTask (socket.ReceiveAsync(segment, cts.Token))
            
            Logger.log.Debug("result: {result}", result)
            let msg = Encoding.UTF8.GetString(buffer)
            Logger.log.Debug("received message:\n{msg}", msg)

            Array.fill buffer 0 buffer.Length 0uy

            return! loop()
        }       

    let subscribeMsg = Encoding.UTF8.GetBytes @"{ ""type"": ""subscribe"" }"
    Async.Start (Async.AwaitTask (socket.SendAsync(ArraySegment(subscribeMsg), WebSocketMessageType.Text, true, cts.Token)))

    loop() |> Async.RunSynchronously

    0 // return an integer exit code