event types in F#

[thomasd3]

The event types for socket message make it difficult to interface with this lib in F#. I'm not sure if this is something in your scope or not though.

[LiveOrDevTrying]

I did not scope this project to work with F# but can modify it. What specifically would you like changed to make it easier to interface with? Ty,

[thomasd3]

Events in F# implement the IEvent type; there is a custom object for it (simply called 'Event'). I think the only thing that would really benefit from a change is the event types. If you create an empty F# project, import WebsocketsSimple's nuget into it and then try to hook to an event, you'll see how different the types are right away. Apart from this, everything else should be smooth.

[LiveOrDevTrying]

I think I understand - I tried it in F#, is it because the events are returnning a Task instead of void?

[thomasd3]

Take this F# example:

open WebsocketsSimple.Client
open WebsocketsSimple.Client.Models

let params = ParamsWSClient(
        Port = 1234,
        Uri = "localhost"
    )

let client = new WebsocketClient(params)
client.ConnectionEvent.Add(fun x -> printfn "event!")

The function passed to the ConnectionEvent is a classic F# lambda, which is quite standard, but here is what the compiler will return:

Program.fs(11, 8): [FS1091] The event 'ConnectionEvent' has a non-standard type. If this event is declared in another CLI language, you may need to access this event using the explicit add_ConnectionEvent and remove_ConnectionEvent methods for the event. If this event is declared in F#, make the type of the event an instantiation of either 'IDelegateEvent<_>' or 'IEvent<_,_>'.

So you can try to add the event through add_ConnectionEvent:

client.add_ConnectionEvent (fun x -> printfn "event!")

But that will not work either because now we need the event to match the right type:

  Program.fs(13, 28): [FS0193] Type constraint mismatch. The type 
    ''a -> unit'    
is not compatible with type
    'PHS.Networking.Events.NetworkingEventHandler<Events.Args.WSConnectionClientEventArgs>'

In the end, the non standard event type is making interfacing quite complex. The solution would be to use an event that has the IEvent type since it's pretty much the standard both in C# and F#.

What is the reason behind having a custom event type?

[LiveOrDevTrying]

Ty, I was able to reproduce this. This is happening because the events are a return type of Task. I can fix this in the next update and will post here. But for my understanding, how do I call an async function in F#? I want to make sure everything is fixed for you.

[thomasd3]

In F#, the async functions have to be explicitly executed.

For example:

let f (x: string) =
    async {
        // do some stuff
        return 1
    }

will have the type string->Async, so if you call it, you will get back an Async.

You can build long chains where you have Async types and then execute them all in cascade.

To answer your question, you can force the execution by calling (in F#) Async.RunSynchronously and this will execute the code inside the async block. To execute from C#, you'd have to await the async block.

This post here: http://tomasp.net/blog/csharp-fsharp-async-intro.aspx/ describes the similarities and differences between the async functions in F# in much better terms than I can.

[LiveOrDevTrying]

Ty again for your feedback. I have made this change in Master and packages have been built. Here is it working in F#:

Thank you again and please let me know if I can be of any more help. Rob