Align lazy and future operators #26446

akka-docs/src/test/scala/docs/stream/operators/SourceOperators.scala

@@ -20,7 +20,7 @@ object SourceOperators {
 
     import scala.concurrent.Future
 
-    val source: Source[Int, NotUsed] = Source.fromFuture(Future.successful(10))
+    val source: Source[Int, NotUsed] = Source.future(Future.successful(10))
     val sink: Sink[Int, Future[Done]] = Sink.foreach((i: Int) => println(i))
 
     val done: Future[Done] = source.runWith(sink) //10

akka-docs/src/test/scala/docs/stream/operators/flow/FutureFlow.scala

@@ -0,0 +1,35 @@
+/*
+ * Copyright (C) 2009-2019 Lightbend Inc. <https://www.lightbend.com>
+ */
+
+package docs.stream.operators.flow
+
+import akka.NotUsed
+import akka.actor.ActorSystem
+import akka.stream.scaladsl.Flow
+import akka.stream.scaladsl.Source
+
+import scala.concurrent.Future
+
+class FutureFlow {
+
+  implicit val system: ActorSystem = ???
+  import system.dispatcher
+
+  def compileOnlyBaseOnFirst(): Unit = {
+    // #base-on-first-element
+    def processingFlow(id: Int): Future[Flow[Int, String, NotUsed]] =
+      Future {
+        Flow[Int].map(n => s"id: $id, value: $n")
+      }
+
+    val source: Source[String, NotUsed] =
+      Source(1 to 10).prefixAndTail(1).flatMapConcat {
+        case (List(id), tail) =>
+          // base the Future flow creation on the first element
+          tail.via(Flow.futureFlow(processingFlow(id)))
+      }
+    // #base-on-first-element
+  }
+
+}