Adds @experimental annotation to lower the acti...

Adds @experimental annotation to lower the activation energy wall
between me and all my good ideas. Then took advantage of same to add
the experimental filterMap to Traversable. (I consider its goodness
undeniable, but its name at least is experimental.)

2 files changed, 30 insertions, 0 deletions

diff --git a/src/library/scala/annotation/experimental.scala b/src/library/scala/annotation/experimental.scala
new file mode 100644
index 0000000000..b33d9ea246
--- /dev/null
+++ b/src/library/scala/annotation/experimental.scala
@@ -0,0 +1,16 @@
+/*                     __                                               *\
+**     ________ ___   / /  ___     Scala API                            **
+**    / __/ __// _ | / /  / _ |    (c) 2002-2009, LAMP/EPFL             **
+**  __\ \/ /__/ __ |/ /__/ __ |    http://scala-lang.org/               **
+** /____/\___/_/ |_/____/_/ | |                                         **
+**                          |/                                          **
+\*                                                                      */
+package scala.annotation
+
+/** <p>
+ *    An annotation for experimental features.
+ *  </p>
+ */
+final class experimental(message: String) extends StaticAnnotation {
+  def this() = this("")
+}
\ No newline at end of file
diff --git a/src/library/scala/collection/generic/TraversableTemplate.scala b/src/library/scala/collection/generic/TraversableTemplate.scala
index 64017b06aa..e053ab4cb4 100644
--- a/src/library/scala/collection/generic/TraversableTemplate.scala
+++ b/src/library/scala/collection/generic/TraversableTemplate.scala
@@ -13,6 +13,7 @@ package scala.collection.generic
 
 // import immutable.{List, Stream, Nil} //!!!
 import mutable.{Buffer, ArrayBuffer, ListBuffer}
+import annotation.experimental
 
 /** A template trait for traversable collections.
  *  This is a base trait of all kinds of Scala collections. It implements
@@ -180,6 +181,19 @@ self =>
     b.result
   }
 
+  /** Returns a new traversable based on the partial function <code>pf</code>,
+  *  containing pf(x) for all the elements which are defined on pf.
+  *  The order of the elements is preserved.
+  *  @param pf the partial function which filters and maps the traversable.
+  *  @return the new traversable.
+  */
+  @experimental
+  def filterMap[B, That](pf: PartialFunction[Any, B])(implicit bf: BuilderFactory[B, That, This]): That = {
+    val b = bf(thisCollection)
+    for (x <- this) if (pf.isDefinedAt(x)) b += pf(x)
+    b.result
+  }
+
   /** Returns a traversable with all elements of this traversable which do not satisfy the predicate
    *  <code>p</code>.
    *