Reverts r20311 since I'm not seeing what's goin...

Reverts r20311 since I'm not seeing what's going on in #2876 and the
optimization can wait.

8 files changed, 125 insertions, 164 deletions

diff --git a/src/library/scala/collection/IndexedSeqViewLike.scala b/src/library/scala/collection/IndexedSeqViewLike.scala
index 5b0b04e5be..07f63ad2b0 100644
--- a/src/library/scala/collection/IndexedSeqViewLike.scala
+++ b/src/library/scala/collection/IndexedSeqViewLike.scala
@@ -24,24 +24,47 @@ import TraversableView.NoBuilder
 trait IndexedSeqViewLike[+A,
                          +Coll,
                          +This <: IndexedSeqView[A, Coll] with IndexedSeqViewLike[A, Coll, This]]
-  extends IndexedSeq[A]
-      with IndexedSeqLike[A, This]
-      with SeqView[A, Coll]
-      with SeqViewLike[A, Coll, This]
-      with views.IndexedSeqTransformations[A, Coll, This]
+  extends IndexedSeq[A] with IndexedSeqLike[A, This] with SeqView[A, Coll] with SeqViewLike[A, Coll, This]
 { self =>
 
-  trait Transformed[+B] extends views.IndexedSeqLike[B, Coll] with super.Transformed[B]
+  trait Transformed[+B] extends IndexedSeqView[B, Coll] with super.Transformed[B]
 
-  trait Sliced extends Transformed[A] with super.Sliced
-  trait Mapped[B] extends Transformed[B] with super.Mapped[B]
-  trait FlatMapped[B] extends Transformed[B] with super.FlatMapped[B]
-  trait Appended[B >: A] extends Transformed[B] with super.Appended[B]
-  trait Filtered extends Transformed[A] with super.Filtered
-  trait TakenWhile extends Transformed[A] with super.TakenWhile
-  trait DroppedWhile extends Transformed[A] with super.DroppedWhile
-  trait Reversed extends Transformed[A] with super.Reversed
-  trait Patched[B >: A] extends Transformed[B] with super.Patched[B]
+  trait Sliced extends Transformed[A] with super.Sliced {
+    /** Override to use IndexedSeq's foreach; todo: see whether this is really faster */
+    override def foreach[U](f: A =>  U) = super[Transformed].foreach(f)
+  }
+
+  trait Mapped[B] extends Transformed[B] with super.Mapped[B] {
+    override def foreach[U](f: B =>  U) = super[Transformed].foreach(f)
+  }
+
+  trait FlatMapped[B] extends Transformed[B] with super.FlatMapped[B] {
+    override def foreach[U](f: B =>  U) = super[Transformed].foreach(f)
+  }
+
+  trait Appended[B >: A] extends Transformed[B] with super.Appended[B] {
+    override def foreach[U](f: B =>  U) = super[Transformed].foreach(f)
+  }
+
+  trait Filtered extends Transformed[A] with super.Filtered {
+    override def foreach[U](f: A =>  U) = super[Transformed].foreach(f)
+  }
+
+  trait TakenWhile extends Transformed[A] with super.TakenWhile {
+    override def foreach[U](f: A =>  U) = super[Transformed].foreach(f)
+  }
+
+  trait DroppedWhile extends Transformed[A] with super.DroppedWhile {
+    override def foreach[U](f: A =>  U) = super[Transformed].foreach(f)
+  }
+
+  trait Reversed extends Transformed[A] with super.Reversed {
+    override def foreach[U](f: A =>  U) = super[Transformed].foreach(f)
+  }
+
+  trait Patched[B >: A] extends Transformed[B] with super.Patched[B] {
+    override def foreach[U](f: B =>  U) = super[Transformed].foreach(f)
+  }
 
   trait Zipped[B] extends Transformed[(A, B)] {
     protected[this] val other: Iterable[B]
@@ -69,5 +92,22 @@ trait IndexedSeqViewLike[+A,
     }
     override def stringPrefix = self.stringPrefix+"Z"
   }
+
+  /** Boilerplate method, to override in each subclass
+   *  This method could be eliminated if Scala had virtual classes
+   */
+  protected override def newAppended[B >: A](that: Traversable[B]): Transformed[B] = new Appended[B] { val rest = that }
+  protected override def newMapped[B](f: A => B): Transformed[B] = new Mapped[B] { val mapping = f }
+  protected override def newFlatMapped[B](f: A => Traversable[B]): Transformed[B] = new FlatMapped[B] { val mapping = f }
+  protected override def newFiltered(p: A => Boolean): Transformed[A] = new Filtered { val pred = p }
+  protected override def newSliced(_from: Int, _until: Int): Transformed[A] = new Sliced { val from = _from; val until = _until }
+  protected override def newDroppedWhile(p: A => Boolean): Transformed[A] = new DroppedWhile { val pred = p }
+  protected override def newTakenWhile(p: A => Boolean): Transformed[A] = new TakenWhile { val pred = p }
+  protected override def newZipped[B](that: Iterable[B]): Transformed[(A, B)] = new Zipped[B] { val other = that }
+  protected override def newZippedAll[A1 >: A, B](that: Iterable[B], _thisElem: A1, _thatElem: B): Transformed[(A1, B)] = new ZippedAll[A1, B] { val other = that; val thisElem = _thisElem; val thatElem = _thatElem }
+  protected override def newReversed: Transformed[A] = new Reversed { }
+  protected override def newPatched[B >: A](_from: Int, _patch: Seq[B], _replaced: Int): Transformed[B] = new Patched[B] {
+    val from = _from; val patch = _patch; val replaced = _replaced
+  }
   override def stringPrefix = "IndexedSeqView"
 }
diff --git a/src/library/scala/collection/IterableViewLike.scala b/src/library/scala/collection/IterableViewLike.scala
index 831a244352..27323294c4 100644
--- a/src/library/scala/collection/IterableViewLike.scala
+++ b/src/library/scala/collection/IterableViewLike.scala
@@ -24,14 +24,10 @@ import TraversableView.NoBuilder
 trait IterableViewLike[+A,
                        +Coll,
                        +This <: IterableView[A, Coll] with IterableViewLike[A, Coll, This]]
-  extends Iterable[A]
-      with IterableLike[A, This]
-      with TraversableView[A, Coll]
-      with TraversableViewLike[A, Coll, This]
-      with views.IterableTransformations[A, Coll, This]
+extends Iterable[A] with IterableLike[A, This] with TraversableView[A, Coll] with TraversableViewLike[A, Coll, This]
 { self =>
 
-  trait Transformed[+B] extends views.IterableLike[B, Coll] with super.Transformed[B]
+  trait Transformed[+B] extends IterableView[B, Coll] with super.Transformed[B]
 
   trait Sliced extends Transformed[A] with super.Sliced {
     override def iterator = self.iterator slice (from, until)
@@ -88,5 +84,25 @@ trait IterableViewLike[+A,
   override def zipAll[B, A1 >: A, That](that: Iterable[B], thisElem: A1, thatElem: B)(implicit bf: CanBuildFrom[This, (A1, B), That]): That =
     newZippedAll(that, thisElem, thatElem).asInstanceOf[That]
 
+  protected def newZipped[B](that: Iterable[B]): Transformed[(A, B)] = new Zipped[B] {
+    val other = that
+  }
+  protected def newZippedAll[A1 >: A, B](that: Iterable[B], _thisElem: A1, _thatElem: B): Transformed[(A1, B)] = new ZippedAll[A1, B] {
+    val other: Iterable[B] = that
+    val thisElem = _thisElem
+    val thatElem = _thatElem
+  }
+
+  /** Boilerplate method, to override in each subclass
+   *  This method could be eliminated if Scala had virtual classes
+   */
+  protected override def newAppended[B >: A](that: Traversable[B]): Transformed[B] = new Appended[B] { val rest = that }
+  protected override def newMapped[B](f: A => B): Transformed[B] = new Mapped[B] { val mapping = f }
+  protected override def newFlatMapped[B](f: A => Traversable[B]): Transformed[B] = new FlatMapped[B] { val mapping = f }
+  protected override def newFiltered(p: A => Boolean): Transformed[A] = new Filtered { val pred = p }
+  protected override def newSliced(_from: Int, _until: Int): Transformed[A] = new Sliced { val from = _from; val until = _until }
+  protected override def newDroppedWhile(p: A => Boolean): Transformed[A] = new DroppedWhile { val pred = p }
+  protected override def newTakenWhile(p: A => Boolean): Transformed[A] = new TakenWhile { val pred = p }
+
   override def stringPrefix = "IterableView"
 }
diff --git a/src/library/scala/collection/SeqViewLike.scala b/src/library/scala/collection/SeqViewLike.scala
index 6f677616e7..1a8cd20013 100644
--- a/src/library/scala/collection/SeqViewLike.scala
+++ b/src/library/scala/collection/SeqViewLike.scala
@@ -23,14 +23,13 @@ import TraversableView.NoBuilder
 trait SeqViewLike[+A,
                            +Coll,
                            +This <: SeqView[A, Coll] with SeqViewLike[A, Coll, This]]
-  extends Seq[A]
-      with SeqLike[A, This]
-      with IterableView[A, Coll]
-      with IterableViewLike[A, Coll, This]
-      with views.SeqTransformations[A, Coll, This]
+  extends Seq[A] with SeqLike[A, This] with IterableView[A, Coll] with IterableViewLike[A, Coll, This]
 { self =>
 
-  trait Transformed[+B] extends views.SeqLike[B, Coll] with super.Transformed[B]
+  trait Transformed[+B] extends SeqView[B, Coll] with super.Transformed[B] {
+    override def length: Int
+    override def apply(idx: Int): B
+  }
 
   trait Sliced extends Transformed[A] with super.Sliced {
     override def length = ((until min self.length) - from) max 0
@@ -144,6 +143,21 @@ trait SeqViewLike[+A,
     override def stringPrefix = self.stringPrefix+"P"
   }
 
+  /** Boilerplate method, to override in each subclass
+   *  This method could be eliminated if Scala had virtual classes
+   */
+  protected override def newAppended[B >: A](that: Traversable[B]): Transformed[B] = new Appended[B] { val rest = that }
+  protected override def newMapped[B](f: A => B): Transformed[B] = new Mapped[B] { val mapping = f }
+  protected override def newFlatMapped[B](f: A => Traversable[B]): Transformed[B] = new FlatMapped[B] { val mapping = f }
+  protected override def newFiltered(p: A => Boolean): Transformed[A] = new Filtered { val pred = p }
+  protected override def newSliced(_from: Int, _until: Int): Transformed[A] = new Sliced { val from = _from; val until = _until }
+  protected override def newDroppedWhile(p: A => Boolean): Transformed[A] = new DroppedWhile { val pred = p }
+  protected override def newTakenWhile(p: A => Boolean): Transformed[A] = new TakenWhile { val pred = p }
+  protected override def newZipped[B](that: Iterable[B]): Transformed[(A, B)] = new Zipped[B] { val other = that }
+  protected override def newZippedAll[A1 >: A, B](that: Iterable[B], _thisElem: A1, _thatElem: B): Transformed[(A1, B)] = new ZippedAll[A1, B] { val other = that; val thisElem = _thisElem; val thatElem = _thatElem }
+  protected def newReversed: Transformed[A] = new Reversed { }
+  protected def newPatched[B >: A](_from: Int, _patch: Seq[B], _replaced: Int): Transformed[B] = new Patched[B] { val from = _from; val patch = _patch; val replaced = _replaced }
+
   override def reverse: This = newReversed.asInstanceOf[This]
 
   override def patch[B >: A, That](from: Int, patch: Seq[B], replaced: Int)(implicit bf: CanBuildFrom[This, B, That]): That = {
diff --git a/src/library/scala/collection/TraversableViewLike.scala b/src/library/scala/collection/TraversableViewLike.scala
index 7f4d0ebd71..84c33296db 100644
--- a/src/library/scala/collection/TraversableViewLike.scala
+++ b/src/library/scala/collection/TraversableViewLike.scala
@@ -33,9 +33,7 @@ import TraversableView.NoBuilder
 trait TraversableViewLike[+A,
                           +Coll,
                           +This <: TraversableView[A, Coll] with TraversableViewLike[A, Coll, This]]
-  extends Traversable[A]
-  with TraversableLike[A, This]
-  with views.TraversableTransformations[A, Coll, This] {
+  extends Traversable[A] with TraversableLike[A, This] {
 self =>
 
   override protected[this] def newBuilder: Builder[A, This] =
@@ -43,16 +41,16 @@ self =>
 
   protected def underlying: Coll
 
-  trait Transformed[+B] extends views.TraversableLike[B, Coll] {
-    lazy val underlying = self.underlying
-  }
-
   def force[B >: A, That](implicit bf: CanBuildFrom[Coll, B, That]) = {
     val b = bf(underlying)
     b ++= this
     b.result()
   }
 
+  trait Transformed[+B] extends TraversableView[B, Coll] {
+    lazy val underlying = self.underlying
+  }
+
   /** pre: from >= 0
    */
   trait Sliced extends Transformed[A] {
@@ -133,6 +131,17 @@ self =>
     override def stringPrefix = self.stringPrefix+"D"
   }
 
+  /** Boilerplate method, to override in each subclass
+   *  This method could be eliminated if Scala had virtual classes
+   */
+  protected def newAppended[B >: A](that: Traversable[B]): Transformed[B] = new Appended[B] { val rest = that }
+  protected def newMapped[B](f: A => B): Transformed[B] = new Mapped[B] { val mapping = f }
+  protected def newFlatMapped[B](f: A => Traversable[B]): Transformed[B] = new FlatMapped[B] { val mapping = f }
+  protected def newFiltered(p: A => Boolean): Transformed[A] = new Filtered { val pred = p }
+  protected def newSliced(_from: Int, _until: Int): Transformed[A] = new Sliced { val from = _from; val until = _until }
+  protected def newDroppedWhile(p: A => Boolean): Transformed[A] = new DroppedWhile { val pred = p }
+  protected def newTakenWhile(p: A => Boolean): Transformed[A] = new TakenWhile { val pred = p }
+
   override def ++[B >: A, That](that: Traversable[B])(implicit bf: CanBuildFrom[This, B, That]): That = {
     newAppended(that).asInstanceOf[That]
 // was:    if (bf.isInstanceOf[ByPassCanBuildFrom]) newAppended(that).asInstanceOf[That]
diff --git a/src/library/scala/collection/mutable/IndexedSeqView.scala b/src/library/scala/collection/mutable/IndexedSeqView.scala
index db1735b543..e864845455 100644
--- a/src/library/scala/collection/mutable/IndexedSeqView.scala
+++ b/src/library/scala/collection/mutable/IndexedSeqView.scala
@@ -13,6 +13,7 @@ package scala.collection
 package mutable
 
 import generic._
+
 import TraversableView.NoBuilder
 
 /** A non-strict view of a mutable IndexedSeq.
@@ -29,7 +30,9 @@ self =>
 
   def update(idx: Int, elem: A)
 
-  trait Transformed[B] extends views.MutableIndexedSeq[B, Coll] with IndexedSeqView[B, Coll] with super.Transformed[B]
+  trait Transformed[B] extends IndexedSeqView[B, Coll] with super.Transformed[B] {
+    def update(idx: Int, elem: B)
+  }
 
   trait Sliced extends Transformed[A] with super.Sliced {
     override def update(idx: Int, elem: A) =
diff --git a/src/library/scala/collection/views/Transformed.scala b/src/library/scala/collection/views/Transformed.scala
deleted file mode 100644
index 189ca127c8..0000000000
--- a/src/library/scala/collection/views/Transformed.scala
+++ /dev/null
@@ -1,128 +0,0 @@
-/*                     __                                               *\
-**     ________ ___   / /  ___     Scala API                            **
-**    / __/ __// _ | / /  / _ |    (c) 2003-2010, LAMP/EPFL             **
-**  __\ \/ /__/ __ |/ /__/ __ |    http://scala-lang.org/               **
-** /____/\___/_/ |_/____/_/ | |                                         **
-**                          |/                                          **
-\*                                                                      */
-
-// $Id$
-
-
-package scala.collection
-package views
-
-import generic.CanBuildFrom
-
-/** These classes act as accumulators for the majority of methods in the
- *  collections hierarchy.  By creating abstract classes rather than using
- *  the traits exclusively, we avoid creating forwarders in dozens of distinct
- *  anonymous classes and reduce the size of scala-library.jar by over 200K.
- */
-private[collection] trait Transformed
-private[collection] abstract class TraversableLike[+B, +Coll] extends TraversableView[B, Coll] with Transformed {
-  override def foreach[C](f: B => C): Unit
-}
-private[collection] abstract class IterableLike[+B, +Coll] extends TraversableLike[B, Coll] with IterableView[B, Coll] {
-  override def iterator: Iterator[B]
-}
-private[collection] abstract class SeqLike[+B, +Coll] extends IterableLike[B, Coll] with SeqView[B, Coll] {
-  override def length: Int
-  override def apply(idx: Int): B
-}
-private[collection] abstract class IndexedSeqLike[+B, +Coll] extends SeqLike[B, Coll] with IndexedSeqView[B, Coll] {
-  /** Override to use IndexedSeq's foreach; todo: see whether this is really faster */
-  override def foreach[U](f: B => U) = super[IndexedSeqView].foreach(f)
-}
-private[collection] abstract class MutableIndexedSeq[B, +Coll] extends IndexedSeqLike[B, Coll] {
-  def update(idx: Int, elem: B)
-}
-
-/** The boilerplate in the following traits factored out of the *ViewLike classes
- *  to reduce noise.  It exists only to specialize the return type of each method.
- *  It would be unnecessary if scala had virtual classes because the inner classes
- *  of subtraits would subclass the parent trait inner classes, and the same method
- *  would then suffice for both.
- */
-private[collection] trait TraversableTransformations[+A, +Coll, +This <: TraversableView[A, Coll] with TraversableViewLike[A, Coll, This]] {
-  self: TraversableViewLike[A, Coll, This] =>
-
-  /** Boilerplate methods, to override in each subclass. */
-  protected def newAppended[B >: A](that: Traversable[B]): Transformed[B] = new Appended[B] { val rest = that }
-  protected def newMapped[B](f: A => B): Transformed[B] = new Mapped[B] { val mapping = f }
-  protected def newFlatMapped[B](f: A => Traversable[B]): Transformed[B] = new FlatMapped[B] { val mapping = f }
-  protected def newFiltered(p: A => Boolean): Transformed[A] = new Filtered { val pred = p }
-  protected def newSliced(_from: Int, _until: Int): Transformed[A] = new Sliced { val from = _from; val until = _until }
-  protected def newDroppedWhile(p: A => Boolean): Transformed[A] = new DroppedWhile { val pred = p }
-  protected def newTakenWhile(p: A => Boolean): Transformed[A] = new TakenWhile { val pred = p }
-}
-
-private[collection] trait IterableTransformations[+A, +Coll, +This <: IterableView[A, Coll] with IterableViewLike[A, Coll, This]]
-  extends TraversableTransformations[A, Coll, This]
-{
-  self: IterableViewLike[A, Coll, This] =>
-
-  /** Inherited from TraversableView */
-  protected override def newAppended[B >: A](that: Traversable[B]): Transformed[B] = new Appended[B] { val rest = that }
-  protected override def newMapped[B](f: A => B): Transformed[B] = new Mapped[B] { val mapping = f }
-  protected override def newFlatMapped[B](f: A => Traversable[B]): Transformed[B] = new FlatMapped[B] { val mapping = f }
-  protected override def newFiltered(p: A => Boolean): Transformed[A] = new Filtered { val pred = p }
-  protected override def newSliced(_from: Int, _until: Int): Transformed[A] = new Sliced { val from = _from; val until = _until }
-  protected override def newDroppedWhile(p: A => Boolean): Transformed[A] = new DroppedWhile { val pred = p }
-  protected override def newTakenWhile(p: A => Boolean): Transformed[A] = new TakenWhile { val pred = p }
-
-  /** IterableView boilerplate contribution */
-  protected def newZipped[B](that: Iterable[B]): Transformed[(A, B)] = new Zipped[B] {
-    val other = that
-  }
-  protected def newZippedAll[A1 >: A, B](that: Iterable[B], _thisElem: A1, _thatElem: B): Transformed[(A1, B)] = new ZippedAll[A1, B] {
-    val other: Iterable[B] = that
-    val thisElem = _thisElem
-    val thatElem = _thatElem
-  }
-}
-
-private[collection] trait SeqTransformations[+A, +Coll, +This <: SeqView[A, Coll] with SeqViewLike[A, Coll, This]]
-  extends IterableTransformations[A, Coll, This]
-{
-  self: SeqViewLike[A, Coll, This] =>
-
-  /** Inherited from IterableView */
-  protected override def newAppended[B >: A](that: Traversable[B]): Transformed[B] = new Appended[B] { val rest = that }
-  protected override def newMapped[B](f: A => B): Transformed[B] = new Mapped[B] { val mapping = f }
-  protected override def newFlatMapped[B](f: A => Traversable[B]): Transformed[B] = new FlatMapped[B] { val mapping = f }
-  protected override def newFiltered(p: A => Boolean): Transformed[A] = new Filtered { val pred = p }
-  protected override def newSliced(_from: Int, _until: Int): Transformed[A] = new Sliced { val from = _from; val until = _until }
-  protected override def newDroppedWhile(p: A => Boolean): Transformed[A] = new DroppedWhile { val pred = p }
-  protected override def newTakenWhile(p: A => Boolean): Transformed[A] = new TakenWhile { val pred = p }
-  protected override def newZipped[B](that: Iterable[B]): Transformed[(A, B)] = new Zipped[B] { val other = that }
-  protected override def newZippedAll[A1 >: A, B](that: Iterable[B], _thisElem: A1, _thatElem: B): Transformed[(A1, B)] =
-    new ZippedAll[A1, B] { val other = that; val thisElem = _thisElem; val thatElem = _thatElem }
-
-  /** SeqView boilerplate contribution */
-  protected def newReversed: Transformed[A] = new Reversed { }
-  protected def newPatched[B >: A](_from: Int, _patch: Seq[B], _replaced: Int): Transformed[B] =
-    new Patched[B] { val from = _from; val patch = _patch; val replaced = _replaced }
-}
-
-private[collection] trait IndexedSeqTransformations[+A, +Coll, +This <: IndexedSeqView[A, Coll] with IndexedSeqViewLike[A, Coll, This]]
-  extends SeqTransformations[A, Coll, This]
-{
-  self: IndexedSeqViewLike[A, Coll, This] =>
-
-  /** Inherited from SeqView */
-  protected override def newAppended[B >: A](that: Traversable[B]): Transformed[B] = new Appended[B] { val rest = that }
-  protected override def newMapped[B](f: A => B): Transformed[B] = new Mapped[B] { val mapping = f }
-  protected override def newFlatMapped[B](f: A => Traversable[B]): Transformed[B] = new FlatMapped[B] { val mapping = f }
-  protected override def newFiltered(p: A => Boolean): Transformed[A] = new Filtered { val pred = p }
-  protected override def newSliced(_from: Int, _until: Int): Transformed[A] = new Sliced { val from = _from; val until = _until }
-  protected override def newDroppedWhile(p: A => Boolean): Transformed[A] = new DroppedWhile { val pred = p }
-  protected override def newTakenWhile(p: A => Boolean): Transformed[A] = new TakenWhile { val pred = p }
-
-  protected override def newZipped[B](that: Iterable[B]): Transformed[(A, B)] = new Zipped[B] { val other = that }
-  protected override def newZippedAll[A1 >: A, B](that: Iterable[B], _thisElem: A1, _thatElem: B): Transformed[(A1, B)] =
-    new ZippedAll[A1, B] { val other = that; val thisElem = _thisElem; val thatElem = _thatElem }
-  protected override def newReversed: Transformed[A] = new Reversed { }
-  protected override def newPatched[B >: A](_from: Int, _patch: Seq[B], _replaced: Int): Transformed[B] =
-    new Patched[B] { val from = _from; val patch = _patch; val replaced = _replaced }
-}
diff --git a/test/files/neg/t2641.check b/test/files/neg/t2641.check
index 07900d0796..771624e8d9 100644
--- a/test/files/neg/t2641.check
+++ b/test/files/neg/t2641.check
@@ -25,7 +25,7 @@ t2641.scala:27: error: illegal inheritance; superclass Any
   trait Sliced extends Transformed[A] with super.Sliced {
                        ^
 t2641.scala:27: error: illegal inheritance; superclass Any
- is not a subclass of the superclass TraversableLike
+ is not a subclass of the superclass Object
  of the mixin trait Sliced
   trait Sliced extends Transformed[A] with super.Sliced {
                                                  ^
diff --git a/test/files/run/bug2876.scala b/test/files/run/bug2876.scala
new file mode 100644
index 0000000000..f71879ebff
--- /dev/null
+++ b/test/files/run/bug2876.scala
@@ -0,0 +1,7 @@
+object Test
+{
+  def main(args: Array[String]): Unit = {
+    "x".view.filter(_ => true).take(1)
+  }
+}
+