Merge pull request #6 from viktorklang/futures-in-scala-2.12-part4

Futures in Scala 2.12: Part 4 — transformWith

Futures-in-Scala-2.12-part-4.md

@@ -17,13 +17,34 @@ Remember to use the solution with the least power which will suffice for the tas
 
 And, before you say anything, yes, `flatMap` and `recoverWith` are implemented in terms of `transformWith` in Scala 2.12!
 
+EDIT:
+
+Here's `flatMap`:
+
+~~~scala
+def flatMap[S](f: T => Future[S])(implicit executor: ExecutionContext): Future[S] = transformWith {
+    case Success(s) => f(s)
+    case Failure(_) => this.asInstanceOf[Future[S]] //Safe cast to reuse current, failed, Future
+  }
+~~~
+
+And here's `recoverWith`:
+
+~~~scala
+ def recoverWith[U >: T](pf: PartialFunction[Throwable, Future[U]])(implicit executor: ExecutionContext): Future[U] =
+    transformWith {
+      case Failure(t) => pf.applyOrElse(t, (_: Throwable) => this) //Pass along current failure if no match
+      case Success(_) => this
+    }
+~~~
+
 ###Benefits:
 
 1. Ultimate power, for when you require it
 
 [Here's the RSS feed of this blog](https://github.com/viktorklang/blog/commits/master.atom) and—as I love feedback—please [share your thoughts](https://github.com/viktorklang/blog/issues/3).
 
-To comment on the blog post itself, [click here](https://github.com/viktorklang/blog/pull/4) and comment on the PR.
+To comment on the blog post itself, [click here](https://github.com/viktorklang/blog/pull/4/files) or [here](https://github.com/viktorklang/blog/pull/6/files) and comment on the PR.
 
 Stay tuned for many more updates about Futures in Scala 2.12!