to enum type and back

[ingo]

For some time now I've been trying to get a little message bus running using 
FutureStreams. It works when the messages are strings. Full code at 
<https://gist.github.com/ingoogni/b29fde37f74216e57abf7ed7812d2a52>

Now I would like to get it working with different message types/kinds. The 
following works in one direction.
    
    
    type
      MsgKind = enum
        mkString,
        mkInt,
        mkFloat
      
      Message* = object
        topic*: string
        id*: string
        msgtype*: string   #"p/s", "req/rep", "reply". req/rep requires id
        case msg*: MsgKind
          of mkString: strVal: string
          of mkInt: intVal: int
          of mkFloat: floatVal: float
    [...]
    
    proc post*(topic:string, msg:string|int|float, id:string = "", 
msgtype:string = "p/s"){.async.}=
      var message = Message(
        topic: topic,
        msg: cast[MsgKind](msg),
        id: id,
        msgType: msgType
      )
      echo type(message.msg) #---> this only tells me MsgKind, not what kind it 
originally was.
      await bus.fsBus.write(message)
    
    
    Run

But how do I go the other way, from `MsgKind` back to for example `int`?

(I also tried it with the big `T`, but failed. There it is the `var bus*` that 
gives me problems)