From 27009707d9f9e81d896ba6a66718ad9961ae993a Mon Sep 17 00:00:00 2001 From: Derek Williams Date: Sun, 3 Apr 2011 10:40:06 -0600 Subject: [PATCH] Add basic documentation to Futures.{sequence,traverse} --- akka-actor/src/main/scala/akka/dispatch/Future.scala | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/akka-actor/src/main/scala/akka/dispatch/Future.scala b/akka-actor/src/main/scala/akka/dispatch/Future.scala index 8d7fcd7390..cfe64a8992 100644 --- a/akka-actor/src/main/scala/akka/dispatch/Future.scala +++ b/akka-actor/src/main/scala/akka/dispatch/Future.scala @@ -156,13 +156,19 @@ object Futures { import scala.collection.generic.CanBuildFrom /** - * FIXME document Futures.sequence + * Simple version of Futures.traverse. Transforms a Traversable[Future[A]] into a Future[Traversable[A]]. + * Useful for reducing many Futures into a single Future. */ def sequence[A, M[_] <: Traversable[_]](in: M[Future[A]], timeout: Long = Actor.TIMEOUT)(implicit cbf: CanBuildFrom[M[Future[A]], A, M[A]]): Future[M[A]] = in.foldLeft(new DefaultCompletableFuture[Builder[A, M[A]]](timeout).completeWithResult(cbf(in)): Future[Builder[A, M[A]]])((fr, fa) => for (r <- fr; a <- fa.asInstanceOf[Future[A]]) yield (r += a)).map(_.result) /** - * FIXME document Futures.traverse + * Transforms a Traversable[A] into a Future[Traversable[B]] using the provided Function A => Future[B]. + * This is useful for performing a parallel map. For example, to apply a function to all items of a list + * in parallel: + * 
+   * val myFutureList = Futures.traverse(myList)(x => Future(myFunc(x)))
+   *
*/ def traverse[A, B, M[_] <: Traversable[_]](in: M[A], timeout: Long = Actor.TIMEOUT)(fn: A => Future[B])(implicit cbf: CanBuildFrom[M[A], B, M[B]]): Future[M[B]] = in.foldLeft(new DefaultCompletableFuture[Builder[B, M[B]]](timeout).completeWithResult(cbf(in)): Future[Builder[B, M[B]]]) { (fr, a) =>