error message for iterator

seqTrace hack (temporary)

2 files changed, 7 insertions, 1 deletions

diff --git a/sources/scala/List.scala b/sources/scala/List.scala
index ddc2570225..162a0c5974 100644
--- a/sources/scala/List.scala
+++ b/sources/scala/List.scala
@@ -62,7 +62,10 @@ trait List[+a] extends Seq[a] {
   def elements: Iterator[a] = new Iterator[a] {
     var current = List.this;
     def hasNext: Boolean = !current.isEmpty;
-    def next: a = { val result = current.head; current = current.tail; result }
+    def next: a = { if( !hasNext )
+		      { error( "next on empty Iterator" ) }
+		    else
+                      { val result = current.head; current = current.tail; result } }
   }
 
   /** Returns the list without its last element.
diff --git a/sources/scala/Predef.scala b/sources/scala/Predef.scala
index f835fdd64a..ebe450a42b 100644
--- a/sources/scala/Predef.scala
+++ b/sources/scala/Predef.scala
@@ -58,4 +58,7 @@ object Predef {
 
     type Triple = Tuple3;
     def Triple[a, b, c](x: a, y: b, z: c) = Tuple3(x, y, z);
+
+    type Trace = SeqTrace;
+    type emptyTrace = SeqTraceNil;
 }