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