Docs: mergeLatest (#28586)

akka-docs/src/test/scala/docs/stream/operators/sourceorflow/MergeLatest.scala

@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) 2020 Lightbend Inc. <https://www.lightbend.com>
+ */
+
+package docs.stream.operators.sourceorflow
+import akka.actor.ActorSystem
+import akka.stream.scaladsl.Source
+
+object MergeLatest extends App {
+  implicit val system = ActorSystem()
+
+  //#mergeLatest
+  val prices = Source(List(100, 101, 99, 103))
+  val quantity = Source(List(1, 3, 4, 2))
+
+  prices
+    .mergeLatest(quantity)
+    .map {
+      case price :: quantity :: Nil => price * quantity
+    }
+    .runForeach(println)
+
+  // prints something like:
+  // 100
+  // 101
+  // 303
+  // 297
+  // 396
+  // 412
+  // 206
+  //#mergeLatest
+}