F# Simple message reader using TCP

Question

I have a review request about this part of the code:

let private startReading (client:TcpClient) (bus:IBus) = 
    //TODO check if that can be changed to rec parameter
    let frameNumber = ref 0
    let rec StartReading (client:TcpClient) =
        async{
            match client with
            | null -> async { return 0 } |> Async.StartAsTask |> ignore
            | _ ->
                match (client.IsConnectionEstablished()) with
                | true ->
                    incr frameNumber
                    DeployService.DeployCabninetService
                    let! messange = MessagingHandler.ReadMessage client

                    match(messange) with
                        | Some data -> 
                            let frameNumber = uint32 frameNumber.Value
                            logger.Info(sprintf "Received message with Frame Number: %i" frameNumber) 

                        | None -> 
                            _logger.Info(sprintf "Client disconnected : %O" client.Client.RemoteEndPoint)
                            return! DisconnectClient client None                                

                    return! StartReading client
                | false ->
                    _logger.Info(sprintf "Client disconnected : %O" client.Client.RemoteEndPoint)
                    return! DisconnectClient client None
        }

    StartReading client |> Async.StartAsTask

It is simple reading message procedure from tcp client in f#, but I feel this can be written more gracefully, especially todo part with frame number incrementation using ref in f# feels wrong.

Any suggestions?

Answer 1

Why do you make this call Async.StartAsTask instead of just return the Async<T> to let the client handle that as needed?

---

let rec StartReading (client:TcpClient) =

I would call it reader and then give it the signature of:

let rec reader frameNo (client:TcpClient) =

in order to get rid of reffor frameNumber.

You can then initially call it:

reader 0 client |> Async.StartAsTask

and recursively:

return! reader (frameNo + 1) client