mailbox.fs

module Channel=
  type Msg=
    |Add of string
    |AddSub of Event<string>
  let messages=new List<string>()
  let inbox=MailboxProcessor.Start (fun b->
      let rec loop state=
        async{
           let! msg=b.Receive()
           match msg with
           |Add str-> match state with
                       |[]->messages.Add str
                       |x->x|>Seq.iter(fun (x:Event<string>)->x.Trigger str)
           |AddSub evt->
                  let newState=evt::state
                  messages|>Seq.iter (fun s->newState|>Seq.iter(fun x->x.Trigger s))
                  messages.Clear()
                  return! loop newState
                  
                        
        }
      loop List.empty
        
    )