Throttle a flow using Akka Stream's new FlowGraph DSL

throttle.scala

val rate = 200 millis
 
def throttled[T]: Flow[T, T] = {
  val tickSource = TickSource(rate, rate, () => () )
  val zip = Zip[T, Unit]
  val in = UndefinedSource[T]
  val out = UndefinedSink[T]
	PartialFlowGraph{ implicit builder =>
	  import FlowGraphImplicits._
	  in ~> zip.left  ~> Flow[(T,Unit)].map{ case (t, _) => t } ~> out
	  tickSource ~> zip.right
	}.toFlow(in, out)
}

Thanks. I think it's awkward that a .throttle method is not built-in in Akka Streams.

btw. note that the above is from the experimental akka streams era. See here for discussion on 2.4.6