(* multicast.sig *)

(* a multicast channel is a way of sending messages to an arbitrary
   number of listeners via ports onto the multicast channel; when a
   message is sent to the multicast channel, it is available via all
   ports onto the multicast channel that existed when the message was
   sent *)

signature MULTICAST =
sig

(* multicast channel *)

type 'a mchan

(* port on a multicast channel *)

type 'a port

(* create a multicast channel *)

val mChannel : unit -> 'a mchan

(* create a port onto a multicast channel *)

val port : 'a mchan -> 'a port

(* send a value to a multicast channel *)

val multicast : 'a mchan * 'a -> unit

(* turn a port into an event that, when synchronized on, will receive
   a value from the port; each time the event is synchronized on, a
   new value will be received *)

val recvEvt : 'a port -> 'a CML.event

(* copy p creates a new port that has the same state as p; i.e.,
   exactly the same messages will be receivable via the new port
   as are receivable via the old port *)

val copy : 'a port -> 'a port

end;