partitionEither-patch.scala

Index: src/library/scala/collection/TraversableLike.scala
===================================================================
--- src/library/scala/collection/TraversableLike.scala	(revision 22850)
+++ src/library/scala/collection/TraversableLike.scala	(working copy)
@@ -313,6 +313,19 @@
     for (x <- this) (if (p(x)) l else r) += x
     (l.result, r.result)
   }
+  /** Partitions this $coll in two ${colls} according to the 
+   * transformation to an Either.
+   *
+   * @param p function that generates an either.
+   * @return a pair of ${coll}s: The first $coll consists of all elements
+   *  mapped to the Left of the either.  The relative order of the elements
+   *  in the resulting ${coll}s is the same as the orginal $coll
+   */
+  def partitionEither[B,C,To,To2](p : A => Either[B,C])(implicit cbf1 : CanBuildFrom[Repr, B, To], cbf2 : CanBuildFrom[Repr, C, To2]) : (To, To2) = {
+    val (left, right) = (cbf1(), cbf2())
+    foreach(p(_).fold(left +=, right +=))
+    (left.result(),right.result())
+  }
 
   /** Partitions this $coll into a map of ${coll}s according to some discriminator function.
    *