--- a/perftests.scala	Wed May 21 15:16:37 2008 +0100
+++ b/perftests.scala	Tue Apr 29 15:03:21 2008 +0100
@@ -37,6 +37,10 @@ object Main{
           Traversable.fromIterable(List.range(1, size)).map((_ : Int) * 2).as[List, Int],
           List.range(1, size).map( (_ : Int) * 2))
 
+     test("map over custom lists", 
+          Traversable.range(1, size).as[sequence.List, Int].map((_ : Int) * 2).as[sequence.List, Int],
+          List.range(1, size).map( (_ : Int) * 2))
+
      test("map over arrays", 
           Traversable.fromArray(Array.range(1, size)).map((_ : Int) * 2).as[Array, Int],
           Array.range(1, size).map( (_ : Int) * 2) 
@@ -48,6 +52,6 @@ object Main{
 
      test("filter over arrays", 
           Traversable.fromArray(Array.range(1, size)).filter( (x : Int) => x % 2 == 0).as[Array, Int],
-          Array.range(1, size).filter( (x : Int) => x % 2 == 0)) 
+          Array.range(1, size).filter( (x : Int) => x % 2 == 0))
   }
 }

--- a/src/main/scala/sequence/list.scala	Wed May 21 15:16:37 2008 +0100
+++ b/src/main/scala/sequence/list.scala	Tue Apr 29 15:03:21 2008 +0100
@@ -38,11 +38,14 @@ object List extends SequenceType{
       if (this eq that.asInstanceOf[AnyRef]) true
       else that match {
         case (that : List[_]) => if (that.length != this.length) false;
-                                 else if (this.isEmpty) true;
-                                 else if (this.head != that.head) false;
-                                 else this.tail.equals(that.tail);
+                                 else equalsSameLength(that); 
 
         case _ => false;
+    }
+
+    private final def equalsSameLength(that : List[_]) = this match {
+      case Nil => true;
+      case (x :: xs) => if (x != that.head) false else this.tail == that.tail
     }
 
     override final def hashCode = hash(0);

--- a/src/main/scala/traversable.scala	Wed May 21 15:16:37 2008 +0100
+++ b/src/main/scala/traversable.scala	Tue Apr 29 15:03:21 2008 +0100
@@ -162,6 +162,18 @@ object Traversable{
     }
   }
 
+  def fromArray[T](it : Array[T]) = new Traversable[T]{
+    def traverse(f : T => Unit) = {
+      var i = 0;
+      while (i < it.length) {
+        f(it(i));
+        i = i + 1;
+      }
+    }
+
+    override def knownSize = Some(it.length);    
+  }
+
   val empty = new Traversable[Nothing]{
     def traverse(f : Nothing => Unit) { }
   }
@@ -193,7 +205,8 @@ object Traversable{
       }
 
     override def take(n : Int) = range(from, Math.min(from + n, until));
-    override def drop(n : Int) = range(from + n, until); 
+    override def drop(n : Int) = range(from + n, until);
+    override def knownSize = until - from;
   }
 
   def break = throw Break;