From 0bef86d8e8b7ea7ebb790ebcec7fedcb9a24f5a8 Mon Sep 17 00:00:00 2001
From: Martin Odersky <odersky@gmail.com>
Date: Thu, 9 Mar 2006 17:50:10 +0000
Subject: performed some renamings in the compiler & library

All -> Bottom
AllRef -> Null
mixin class -> trait
---
 .../scala/tools/nsc/CompilationUnits.scala         |  2 +-
 src/compiler/scala/tools/nsc/EvalLoop.scala        |  2 +-
 .../scala/tools/nsc/ast/TreePrinters.scala         |  4 ++--
 src/compiler/scala/tools/nsc/ast/Trees.scala       | 10 ++++-----
 .../scala/tools/nsc/ast/parser/MarkupParsers.scala |  2 +-
 .../scala/tools/nsc/ast/parser/Parsers.scala       | 26 +++++++++-------------
 .../scala/tools/nsc/ast/parser/Scanners.scala      | 10 +++++++--
 .../scala/tools/nsc/ast/parser/Tokens.scala        |  1 -
 .../tools/nsc/backend/WorklistAlgorithm.scala      |  2 +-
 .../tools/nsc/backend/icode/BasicBlocks.scala      |  2 +-
 .../nsc/backend/icode/ExceptionHandlers.scala      |  2 +-
 .../tools/nsc/backend/icode/Linearizers.scala      |  2 +-
 .../scala/tools/nsc/backend/icode/Members.scala    |  2 +-
 .../scala/tools/nsc/backend/icode/Opcodes.scala    |  2 +-
 .../scala/tools/nsc/backend/icode/Primitives.scala |  2 +-
 .../scala/tools/nsc/backend/icode/TypeKinds.scala  |  2 +-
 .../scala/tools/nsc/backend/icode/TypeStacks.scala |  2 +-
 src/compiler/scala/tools/nsc/doc/DocUtil.scala     |  2 +-
 src/compiler/scala/tools/nsc/models/Models.scala   |  6 ++---
 .../scala/tools/nsc/models/SemanticTokens.scala    |  4 ++--
 .../scala/tools/nsc/symtab/Constants.scala         |  2 +-
 .../scala/tools/nsc/symtab/Definitions.scala       |  6 ++---
 src/compiler/scala/tools/nsc/symtab/Flags.scala    |  8 +++----
 .../scala/tools/nsc/symtab/InfoTransformers.scala  |  2 +-
 src/compiler/scala/tools/nsc/symtab/Scopes.scala   |  2 +-
 src/compiler/scala/tools/nsc/symtab/StdNames.scala |  2 +-
 src/compiler/scala/tools/nsc/symtab/Symbols.scala  | 14 +++++++-----
 src/compiler/scala/tools/nsc/symtab/Types.scala    |  4 ++--
 .../nsc/symtab/classfile/ClassfileParser.scala     |  2 +-
 .../scala/tools/nsc/transform/AddInterfaces.scala  |  2 +-
 .../scala/tools/nsc/transform/Erasure.scala        |  2 +-
 .../scala/tools/nsc/transform/ExplicitOuter.scala  | 12 +++++-----
 src/compiler/scala/tools/nsc/transform/Mixin.scala |  8 +++----
 .../scala/tools/nsc/typechecker/Analyzer.scala     |  2 +-
 .../scala/tools/nsc/typechecker/Codification.scala |  2 +-
 .../scala/tools/nsc/typechecker/Contexts.scala     |  2 +-
 .../scala/tools/nsc/typechecker/EtaExpansion.scala |  2 +-
 .../scala/tools/nsc/typechecker/Infer.scala        |  2 +-
 .../scala/tools/nsc/typechecker/Namers.scala       |  8 +++----
 .../scala/tools/nsc/typechecker/RefChecks.scala    |  8 +++----
 .../tools/nsc/typechecker/SuperAccessors.scala     |  2 +-
 .../tools/nsc/typechecker/SyntheticMethods.scala   |  2 +-
 .../scala/tools/nsc/typechecker/Typers.scala       | 13 +++++------
 .../scala/tools/nsc/typechecker/Variances.scala    |  2 +-
 src/library/scala/Application.scala                |  2 +-
 src/library/scala/BufferedIterator.scala           |  4 ++--
 src/library/scala/CaseClass.scala                  |  2 +-
 src/library/scala/CountedIterator.scala            |  2 +-
 src/library/scala/Function0.scala                  |  2 +-
 src/library/scala/Function1.scala                  |  2 +-
 src/library/scala/Function2.scala                  |  2 +-
 src/library/scala/Function3.scala                  |  2 +-
 src/library/scala/Function4.scala                  |  2 +-
 src/library/scala/Function5.scala                  |  2 +-
 src/library/scala/Function6.scala                  |  2 +-
 src/library/scala/Function7.scala                  |  2 +-
 src/library/scala/Function8.scala                  |  2 +-
 src/library/scala/Function9.scala                  |  2 +-
 src/library/scala/Iterable.scala                   |  2 +-
 src/library/scala/IterableProxy.scala              |  2 +-
 src/library/scala/Iterator.scala                   |  2 +-
 src/library/scala/List.scala                       |  4 ++--
 src/library/scala/MatchError.scala                 |  3 ++-
 src/library/scala/None.scala                       | 20 -----------------
 src/library/scala/Option.scala                     | 18 ++++++++++++++-
 src/library/scala/Ordered.scala                    |  2 +-
 src/library/scala/PartialFunction.scala            |  2 +-
 src/library/scala/PartiallyOrdered.scala           |  2 +-
 src/library/scala/Predef.scala                     |  9 +++++---
 src/library/scala/Proxy.scala                      |  2 +-
 src/library/scala/ScalaObject.scala                |  2 +-
 src/library/scala/SeqProxy.scala                   |  2 +-
 src/library/scala/Some.scala                       | 21 -----------------
 src/library/scala/Stream.scala                     |  6 ++---
 .../collection/mutable/DoubleLinkedList.scala      |  2 +-
 .../collection/mutable/SingleLinkedList.scala      |  2 +-
 src/library/scala/concurrent/MailBox.scala         |  2 +-
 .../scala/dbc/datatype/CharacterString.scala       |  8 +++----
 src/library/scala/runtime/ScalaRunTime.scala       |  2 +-
 79 files changed, 160 insertions(+), 183 deletions(-)
 delete mode 100644 src/library/scala/None.scala
 delete mode 100644 src/library/scala/Some.scala

(limited to 'src')

diff --git a/src/compiler/scala/tools/nsc/CompilationUnits.scala b/src/compiler/scala/tools/nsc/CompilationUnits.scala
index 30a4e77064..d22e3abfa5 100644
--- a/src/compiler/scala/tools/nsc/CompilationUnits.scala
+++ b/src/compiler/scala/tools/nsc/CompilationUnits.scala
@@ -10,7 +10,7 @@ import scala.tools.nsc.util.FreshNameCreator;
 import scala.tools.util.AbstractFile;
 import scala.collection.mutable.HashSet;
 
-mixin class CompilationUnits requires Global {
+trait CompilationUnits requires Global {
 
   class CompilationUnit(val source: SourceFile, val mixinOnly: boolean) {
 
diff --git a/src/compiler/scala/tools/nsc/EvalLoop.scala b/src/compiler/scala/tools/nsc/EvalLoop.scala
index fc6c30f27a..12e9fdeb18 100644
--- a/src/compiler/scala/tools/nsc/EvalLoop.scala
+++ b/src/compiler/scala/tools/nsc/EvalLoop.scala
@@ -1,6 +1,6 @@
 package scala.tools.nsc;
 
-mixin class EvalLoop {
+trait EvalLoop {
 
   def prompt: String;
 
diff --git a/src/compiler/scala/tools/nsc/ast/TreePrinters.scala b/src/compiler/scala/tools/nsc/ast/TreePrinters.scala
index d0ccc76479..3477a84f03 100644
--- a/src/compiler/scala/tools/nsc/ast/TreePrinters.scala
+++ b/src/compiler/scala/tools/nsc/ast/TreePrinters.scala
@@ -118,9 +118,9 @@ abstract class TreePrinters {
         case ClassDef(mods, name, tparams, tp, impl) =>
           printAttributes(tree.symbol.attributes);
           printModifiers(tree, mods);
-	  print("class " + symName(tree, name));
+	  print((if (mods hasFlag TRAIT) "trait " else "class ") + symName(tree, name));
           printTypeParams(tparams);
-          printOpt(": ", tp); print(" extends "); print(impl);
+          printOpt("requires ", tp); print(" extends "); print(impl);
 
         case PackageDef(packaged, stats) =>
           print("package "); print(packaged); printColumn(stats, " {", ";", "}")
diff --git a/src/compiler/scala/tools/nsc/ast/Trees.scala b/src/compiler/scala/tools/nsc/ast/Trees.scala
index e95d41bdd6..763e53d606 100644
--- a/src/compiler/scala/tools/nsc/ast/Trees.scala
+++ b/src/compiler/scala/tools/nsc/ast/Trees.scala
@@ -12,7 +12,7 @@ import scala.tools.nsc.util.{Position,SourceFile};
 import symtab.Flags._;
 
 
-mixin class Trees requires Global {
+trait Trees requires Global {
   //statistics
   var nodeCount = 0;
 
@@ -27,7 +27,7 @@ mixin class Trees requires Global {
     def isCase      = ((flags & CASE    ) != 0);
     def isSealed    = ((flags & SEALED) != 0);
     def isFinal     = ((flags & FINAL   ) != 0);
-    def isMixin     = ((flags & MIXIN   ) != 0);
+    def isTrait     = ((flags & TRAIT   ) != 0);
     def isPublic    = !isPrivate && !isProtected;
     def hasFlag(flag: int) = (flags & flag) != 0;
     def | (flag: int): Modifiers = {
@@ -90,7 +90,7 @@ mixin class Trees requires Global {
     }
   }
 
-  mixin class SymTree extends Tree {
+  trait SymTree extends Tree {
     override def hasSymbol = true;
     override var symbol: Symbol = NoSymbol;
   }
@@ -100,11 +100,11 @@ mixin class Trees requires Global {
     override def isDef = true;
   }
 
-  mixin class TermTree extends Tree {
+  trait TermTree extends Tree {
     override def isTerm = true
   }
 
-  mixin class TypTree extends Tree {
+  trait TypTree extends Tree {
     override def isType = true
   }
 
diff --git a/src/compiler/scala/tools/nsc/ast/parser/MarkupParsers.scala b/src/compiler/scala/tools/nsc/ast/parser/MarkupParsers.scala
index a74d6d4ba1..252288f750 100644
--- a/src/compiler/scala/tools/nsc/ast/parser/MarkupParsers.scala
+++ b/src/compiler/scala/tools/nsc/ast/parser/MarkupParsers.scala
@@ -11,7 +11,7 @@ import scala.tools.nsc.util.Position;
 import scala.xml.{Text,TextBuffer};
 
 
-mixin class MarkupParsers requires SyntaxAnalyzer {
+trait MarkupParsers requires SyntaxAnalyzer {
 
   import global._ ;
   import posAssigner.atPos;
diff --git a/src/compiler/scala/tools/nsc/ast/parser/Parsers.scala b/src/compiler/scala/tools/nsc/ast/parser/Parsers.scala
index c02d59ce86..fe2eebb66a 100644
--- a/src/compiler/scala/tools/nsc/ast/parser/Parsers.scala
+++ b/src/compiler/scala/tools/nsc/ast/parser/Parsers.scala
@@ -38,7 +38,7 @@ import Tokens._;
  *  (4) Wraps naked case definitions in a match as follows:
  *        { cases }   ==>   (x => x.match {cases}), except when already argument to match
  */
-mixin class Parsers requires SyntaxAnalyzer {
+trait Parsers requires SyntaxAnalyzer {
 
   import global._;
   import posAssigner.atPos;
@@ -157,7 +157,7 @@ mixin class Parsers requires SyntaxAnalyzer {
 
     def isDefIntro: boolean = in.token match {
       case VAL | VAR | DEF | TYPE | OBJECT |
-           CASEOBJECT | CLASS | CASECLASS | MIXIN | TRAIT => true
+           CASEOBJECT | CLASS | CASECLASS | TRAIT => true
       case _ => false
     }
 
@@ -324,8 +324,7 @@ mixin class Parsers requires SyntaxAnalyzer {
 	in.nextToken();
 	name
       } else {
-        if (settings.migrate.value &&
-            in.token == REQUIRES || in.token == IMPLICIT || in.token == MIXIN)
+        if (settings.migrate.value && in.token == REQUIRES || in.token == IMPLICIT)
           syntaxErrorMigrate(""+in+" is now a reserved word; cannot be used as identifier");
 	accept(IDENTIFIER);
 	nme.ERROR
@@ -852,7 +851,7 @@ mixin class Parsers requires SyntaxAnalyzer {
           if (settings.migrate.value) {
             if (in.token == MATCH)
               syntaxErrorMigrate("`match' must be preceded by a selector expression")
-            else if (in.token == REQUIRES || in.token == IMPLICIT || in.token == MIXIN)
+            else if (in.token == REQUIRES || in.token == IMPLICIT)
               syntaxErrorMigrate(""+in+" is now a reserved word; cannot be used as identifier");
           }
 	  syntaxError("illegal start of simple expression", true);
@@ -1101,7 +1100,7 @@ mixin class Parsers requires SyntaxAnalyzer {
         r
       case _ =>
         if (settings.migrate.value &&
-            in.token == REQUIRES || in.token == IMPLICIT || in.token == MIXIN)
+            in.token == REQUIRES || in.token == IMPLICIT)
           syntaxErrorMigrate(""+in+" is now a reserved word; cannot be used as identifier");
 	syntaxError("illegal start of simple pattern", true);
 	errorPatternTree
@@ -1575,15 +1574,11 @@ mixin class Parsers requires SyntaxAnalyzer {
 
     /**  TmplDef ::= [case] class ClassDef
      *            |  [case] object ObjectDef
-     *            |  ([mixin class | trait]) MixinClassDef
+     *            |  trait MixinClassDef
      */
     def tmplDef(mods: Modifiers): Tree = in.token match {
       case TRAIT =>
-        classDef(mods | Flags.MIXIN | Flags.ABSTRACT);
-      case MIXIN =>
-        in.nextToken();
-        if (in.token != CLASS) accept(CLASS);
-        classDef(mods | Flags.MIXIN | Flags.ABSTRACT);
+        classDef(mods | Flags.TRAIT | Flags.ABSTRACT);
       case CLASS =>
         classDef(mods);
       case CASECLASS =>
@@ -1609,7 +1604,7 @@ mixin class Parsers requires SyntaxAnalyzer {
 	val vparamss = paramClauses(name, implicitViews.toList, mods.hasFlag(Flags.CASE));
 	val thistpe = requiresTypeOpt();
 	val template = classTemplate(mods, name, vparamss);
-	val mods1 = if (mods.hasFlag(Flags.MIXIN) && (template.body forall treeInfo.isInterfaceMember))
+	val mods1 = if (mods.hasFlag(Flags.TRAIT) && (template.body forall treeInfo.isInterfaceMember))
                       mods | Flags.INTERFACE
                     else mods;
 	ClassDef(mods1, name, tparams, thistpe, template)
@@ -1666,7 +1661,7 @@ mixin class Parsers requires SyntaxAnalyzer {
 	var body =
 	  if (in.token == LBRACE) templateBody()
 	  else { acceptEmptyTemplateBody("`{' expected"); List() }
-	if (!mods.hasFlag(Flags.MIXIN)) Template(ps, vparamss, argss.toList, body)
+	if (!mods.hasFlag(Flags.TRAIT)) Template(ps, vparamss, argss.toList, body)
 	else Template(ps, body)
       }
 
@@ -1721,7 +1716,6 @@ mixin class Parsers requires SyntaxAnalyzer {
         } else if (in.token == CLASS ||
                    in.token == CASECLASS ||
                    in.token == TRAIT ||
-                   in.token == MIXIN ||
                    in.token == OBJECT ||
                    in.token == CASEOBJECT ||
                    in.token == LBRACKET ||
@@ -1800,7 +1794,7 @@ mixin class Parsers requires SyntaxAnalyzer {
 	case _ =>
           false
       }
-      if (attrs exists isMixinAttribute) Flags.MIXIN else 0
+      if (attrs exists isMixinAttribute) Flags.TRAIT else 0
     }
 
     def joinAttributes(attrs: List[Tree], defs: List[Tree]): List[Tree] =
diff --git a/src/compiler/scala/tools/nsc/ast/parser/Scanners.scala b/src/compiler/scala/tools/nsc/ast/parser/Scanners.scala
index 1266252ffd..a38153f28c 100644
--- a/src/compiler/scala/tools/nsc/ast/parser/Scanners.scala
+++ b/src/compiler/scala/tools/nsc/ast/parser/Scanners.scala
@@ -10,7 +10,7 @@ import scala.tools.nsc.util.{Position, SourceFile}
 import SourceFile.{LF, FF, CR, SU}
 import scala.tools.nsc.util.CharArrayReader
 
-mixin class Scanners requires SyntaxAnalyzer {
+trait Scanners requires SyntaxAnalyzer {
 
   import global._
 
@@ -167,6 +167,13 @@ mixin class Scanners requires SyntaxAnalyzer {
           next.copyFrom(this)
           this.copyFrom(prev)
         }
+      } else if (token == IDENTIFIER && name == nme.MIXINkw) { //todo: remove eventually
+        prev.copyFrom(this);
+        fetchToken();
+        if (token == CLASS)
+          unit.warning(pos, "`mixin' is no longer a reserved word; you should use `trait' instead of `mixin class'");
+        next.copyFrom(this)
+        this.copyFrom(prev)
       }
 
       if (afterLineEnd() && inLastOfStat(lastToken) && inFirstOfStat(token) &&
@@ -786,7 +793,6 @@ mixin class Scanners requires SyntaxAnalyzer {
       enterKeyword(nme.IMPLICITkw, IMPLICIT)
       enterKeyword(nme.IMPORTkw, IMPORT)
       enterKeyword(nme.MATCHkw, MATCH)
-      enterKeyword(nme.MIXINkw, MIXIN)
       enterKeyword(nme.NEWkw, NEW)
       enterKeyword(nme.NULLkw, NULL)
       enterKeyword(nme.OBJECTkw, OBJECT)
diff --git a/src/compiler/scala/tools/nsc/ast/parser/Tokens.scala b/src/compiler/scala/tools/nsc/ast/parser/Tokens.scala
index 2f07497ede..b99ee08811 100644
--- a/src/compiler/scala/tools/nsc/ast/parser/Tokens.scala
+++ b/src/compiler/scala/tools/nsc/ast/parser/Tokens.scala
@@ -67,7 +67,6 @@ object Tokens {
   final val RETURN = 57;
   final val MATCH = 58;
   final val REQUIRES = 59;
-  final val MIXIN = 60;
 
   /** special symbols */
   final val COMMA = 61;
diff --git a/src/compiler/scala/tools/nsc/backend/WorklistAlgorithm.scala b/src/compiler/scala/tools/nsc/backend/WorklistAlgorithm.scala
index 3a13767900..d6b81a84fe 100644
--- a/src/compiler/scala/tools/nsc/backend/WorklistAlgorithm.scala
+++ b/src/compiler/scala/tools/nsc/backend/WorklistAlgorithm.scala
@@ -22,7 +22,7 @@ import scala.collection.mutable.MutableList;
  *
  * @see scala.tools.nsc.backend.icode.Linearizers
  */
-mixin class WorklistAlgorithm {
+trait WorklistAlgorithm {
   type Elem;
   type WList <: MutableList[Elem];
 
diff --git a/src/compiler/scala/tools/nsc/backend/icode/BasicBlocks.scala b/src/compiler/scala/tools/nsc/backend/icode/BasicBlocks.scala
index aa42da4273..0c9d6dc2c3 100644
--- a/src/compiler/scala/tools/nsc/backend/icode/BasicBlocks.scala
+++ b/src/compiler/scala/tools/nsc/backend/icode/BasicBlocks.scala
@@ -11,7 +11,7 @@ import scala.tools.nsc.ast._;
 import scala.collection.mutable.Map;
 import scala.tools.nsc.util.Position;
 
-mixin class BasicBlocks requires ICodes {
+trait BasicBlocks requires ICodes {
   import opcodes._;
 
   /** This class represents a basic block. Each
diff --git a/src/compiler/scala/tools/nsc/backend/icode/ExceptionHandlers.scala b/src/compiler/scala/tools/nsc/backend/icode/ExceptionHandlers.scala
index 1e80d0eac0..aa20ecb932 100644
--- a/src/compiler/scala/tools/nsc/backend/icode/ExceptionHandlers.scala
+++ b/src/compiler/scala/tools/nsc/backend/icode/ExceptionHandlers.scala
@@ -17,7 +17,7 @@ import scala.collection.mutable.HashSet;
  * all our handlers will catch `Throwable' and rely on proper ordering
  * in the generated code to preserve nesting.
  */
-mixin class ExceptionHandlers requires ICodes {
+trait ExceptionHandlers requires ICodes {
   import global.{Symbol, NoSymbol};
 
   class ExceptionHandler(val method: IMethod, label: String, val cls: Symbol) {
diff --git a/src/compiler/scala/tools/nsc/backend/icode/Linearizers.scala b/src/compiler/scala/tools/nsc/backend/icode/Linearizers.scala
index c0b6ada3c3..ff4a2d4a0a 100644
--- a/src/compiler/scala/tools/nsc/backend/icode/Linearizers.scala
+++ b/src/compiler/scala/tools/nsc/backend/icode/Linearizers.scala
@@ -10,7 +10,7 @@ package scala.tools.nsc.backend.icode;
 import scala.tools.nsc.ast._;
 import scala.collection.mutable.{Stack, HashSet};
 
-mixin class Linearizers requires ICodes {
+trait Linearizers requires ICodes {
   import opcodes._;
 
   abstract class Linearizer {
diff --git a/src/compiler/scala/tools/nsc/backend/icode/Members.scala b/src/compiler/scala/tools/nsc/backend/icode/Members.scala
index 02af695f37..e9e6445185 100644
--- a/src/compiler/scala/tools/nsc/backend/icode/Members.scala
+++ b/src/compiler/scala/tools/nsc/backend/icode/Members.scala
@@ -13,7 +13,7 @@ import scala.{Symbol => scala_Symbol};
 
 import scala.tools.nsc.symtab.Flags;
 
-mixin class Members requires ICodes {
+trait Members requires ICodes {
   import global._;
 
   /**
diff --git a/src/compiler/scala/tools/nsc/backend/icode/Opcodes.scala b/src/compiler/scala/tools/nsc/backend/icode/Opcodes.scala
index 57fa0ff327..912358762c 100644
--- a/src/compiler/scala/tools/nsc/backend/icode/Opcodes.scala
+++ b/src/compiler/scala/tools/nsc/backend/icode/Opcodes.scala
@@ -48,7 +48,7 @@ import scala.tools.nsc.util.Position;
  * erased types of Scala and references Symbols to refer named entities
  * in the source files.
  */
-mixin class Opcodes requires ICodes {
+trait Opcodes requires ICodes {
   import global.{Symbol, NoSymbol, Type, Name, Constant};
 
   /** This class represents an instruction of the intermediate code.
diff --git a/src/compiler/scala/tools/nsc/backend/icode/Primitives.scala b/src/compiler/scala/tools/nsc/backend/icode/Primitives.scala
index b134819853..c07b7b0829 100644
--- a/src/compiler/scala/tools/nsc/backend/icode/Primitives.scala
+++ b/src/compiler/scala/tools/nsc/backend/icode/Primitives.scala
@@ -9,7 +9,7 @@ package scala.tools.nsc.backend.icode;
 
 import java.io.PrintWriter;
 
-mixin class Primitives requires ICodes {
+trait Primitives requires ICodes {
 
   /** This class represents a primitive operation. */
   class Primitive {
diff --git a/src/compiler/scala/tools/nsc/backend/icode/TypeKinds.scala b/src/compiler/scala/tools/nsc/backend/icode/TypeKinds.scala
index 362aeb9100..ce2895c8c7 100644
--- a/src/compiler/scala/tools/nsc/backend/icode/TypeKinds.scala
+++ b/src/compiler/scala/tools/nsc/backend/icode/TypeKinds.scala
@@ -25,7 +25,7 @@ package scala.tools.nsc.backend.icode;
 
 import scala.collection.mutable.{Map, HashMap};
 
-mixin class TypeKinds requires ICodes {
+trait TypeKinds requires ICodes {
   import global._;
 
   /** This class represents a type kind. Type kinds
diff --git a/src/compiler/scala/tools/nsc/backend/icode/TypeStacks.scala b/src/compiler/scala/tools/nsc/backend/icode/TypeStacks.scala
index 6aa8507c57..69f1f34cb7 100644
--- a/src/compiler/scala/tools/nsc/backend/icode/TypeStacks.scala
+++ b/src/compiler/scala/tools/nsc/backend/icode/TypeStacks.scala
@@ -9,7 +9,7 @@ package scala.tools.nsc.backend.icode;
 
 import scala.tools.nsc.backend.icode.Primitives;
 
-mixin class TypeStacks requires ICodes {
+trait TypeStacks requires ICodes {
   import opcodes._;
   import global.{Symbol, Type, definitions};
 
diff --git a/src/compiler/scala/tools/nsc/doc/DocUtil.scala b/src/compiler/scala/tools/nsc/doc/DocUtil.scala
index c88b1cac35..e7a0d6cf88 100644
--- a/src/compiler/scala/tools/nsc/doc/DocUtil.scala
+++ b/src/compiler/scala/tools/nsc/doc/DocUtil.scala
@@ -26,7 +26,7 @@ object DocUtil {
     nodes.concat(x)
   }
 
-  mixin class UrlContext {
+  trait UrlContext {
     def relative: String
 
     def aref(href0: String, target: String, text: String): NodeSeq = {
diff --git a/src/compiler/scala/tools/nsc/models/Models.scala b/src/compiler/scala/tools/nsc/models/Models.scala
index f89e2da145..65eb769d67 100644
--- a/src/compiler/scala/tools/nsc/models/Models.scala
+++ b/src/compiler/scala/tools/nsc/models/Models.scala
@@ -47,7 +47,7 @@ abstract class Models {
     if (mods . isCase     ) modString = "case"      :: modString;
     if (mods . isSealed   ) modString = "sealed"    :: modString;
     if (mods . isFinal    ) modString = "final"    :: modString;
-    if (mods . isMixin    ) modString = "mixin"    :: modString;
+    if (mods . isTrait    ) modString = "mixin"    :: modString;
     modString;
   }
 
@@ -161,7 +161,7 @@ abstract class Models {
 	    def treex = tree.asInstanceOf[PackageDef];
 	}
 
-  mixin class Composite extends Model {
+  trait Composite extends Model {
     import scala.collection.mutable._;
 
 
@@ -245,7 +245,7 @@ abstract class Models {
   }
   abstract class MemberComposite(parent0: Composite) extends MemberMod(parent0) with Composite;
 
-  mixin class HasClassObjects extends Composite {
+  trait HasClassObjects extends Composite {
     override def isMember(tree : Tree) : Boolean = (super.isMember(tree) ||
       (tree.isInstanceOf[ImplDef]));
   }
diff --git a/src/compiler/scala/tools/nsc/models/SemanticTokens.scala b/src/compiler/scala/tools/nsc/models/SemanticTokens.scala
index ef8f60e6c8..c345226633 100644
--- a/src/compiler/scala/tools/nsc/models/SemanticTokens.scala
+++ b/src/compiler/scala/tools/nsc/models/SemanticTokens.scala
@@ -50,12 +50,12 @@ class SemanticTokens(val compiler: Global) {
     else pos;
   }
 
-  mixin class HasNext extends Token {
+  trait HasNext extends Token {
     var next0: HasPrev = _;
     def next = next0;
   }
 
-  mixin class HasPrev extends Token {
+  trait HasPrev extends Token {
     var prev0: HasNext = _;
     def prev = prev0;
   }
diff --git a/src/compiler/scala/tools/nsc/symtab/Constants.scala b/src/compiler/scala/tools/nsc/symtab/Constants.scala
index 48a0c0bdf0..263a02a46a 100644
--- a/src/compiler/scala/tools/nsc/symtab/Constants.scala
+++ b/src/compiler/scala/tools/nsc/symtab/Constants.scala
@@ -9,7 +9,7 @@ package scala.tools.nsc.symtab;
 
 import classfile.PickleFormat._;
 
-mixin class Constants requires SymbolTable {
+trait Constants requires SymbolTable {
 
   import definitions._;
 
diff --git a/src/compiler/scala/tools/nsc/symtab/Definitions.scala b/src/compiler/scala/tools/nsc/symtab/Definitions.scala
index 4d2c3466f9..81a9448ddd 100644
--- a/src/compiler/scala/tools/nsc/symtab/Definitions.scala
+++ b/src/compiler/scala/tools/nsc/symtab/Definitions.scala
@@ -9,7 +9,7 @@ import scala.tools.nsc.util.Position;
 import collection.mutable.HashMap;
 import Flags._;
 
-mixin class Definitions requires SymbolTable {
+trait Definitions requires SymbolTable {
 
   object definitions {
     def isDefinitionsInitialized = isInitialized;
@@ -318,10 +318,10 @@ mixin class Definitions requires SymbolTable {
       AnyRefClass = newAlias(ScalaPackageClass, "AnyRef", ObjectClass.typeConstructor);
 
       AllRefClass = newClass(ScalaPackageClass, "AllRef", List(AnyRefClass.typeConstructor))
-	.setFlag(ABSTRACT | MIXIN | FINAL);
+	.setFlag(ABSTRACT | TRAIT | FINAL);
 
       AllClass = newClass(ScalaPackageClass, "All", List(AnyClass.typeConstructor))
-	.setFlag(ABSTRACT | MIXIN | FINAL);
+	.setFlag(ABSTRACT | TRAIT | FINAL);
 
       StringClass = getClass("java.lang.String");
       ThrowableClass = getClass("java.lang.Throwable");
diff --git a/src/compiler/scala/tools/nsc/symtab/Flags.scala b/src/compiler/scala/tools/nsc/symtab/Flags.scala
index 2c9bc04b69..d54a12159b 100644
--- a/src/compiler/scala/tools/nsc/symtab/Flags.scala
+++ b/src/compiler/scala/tools/nsc/symtab/Flags.scala
@@ -48,7 +48,7 @@ object Flags {
   final val STATIC        = 0x00800000;   // static field, method or class
 
   final val CASEACCESSOR  = 0x01000000;   // symbol is a case parameter (or its accessor)
-  final val MIXIN         = 0x02000000;   // symbol is a mixin class
+  final val TRAIT         = 0x02000000;   // symbol is a trait
   final val BRIDGE        = 0x04000000;   // function is a bridge method. Set by Erasure
   final val ACCESSOR      = 0x08000000;   // a value or variable accessor
 
@@ -99,8 +99,8 @@ object Flags {
   final val TopLevelCreationFlags =
     MODULE | PACKAGE | FINAL | JAVA;
 
-  final val ExplicitFlags =                // these modifiers can be set explicitly in source programs.
-    PRIVATE | PROTECTED | ABSTRACT | MIXIN | FINAL | SEALED | OVERRIDE | CASE | IMPLICIT | ABSOVERRIDE;
+  final val ExplicitFlags =       // these modifiers can be set explicitly in source programs.
+    PRIVATE | PROTECTED | ABSTRACT | FINAL | SEALED | OVERRIDE | CASE | IMPLICIT | ABSOVERRIDE;
 
   final val PrintableFlags =               // these modifiers appear in TreePrinter output.
     (ExplicitFlags | LOCAL | SYNTHETIC | STABLE | CASEACCESSOR | ACCESSOR |
@@ -161,7 +161,7 @@ object Flags {
       case STATIC        => "<static>"
 
       case CASEACCESSOR  => "<caseaccessor>"
-      case MIXIN         => "mixin"
+      case TRAIT         => "<trait>"
       case BRIDGE        => "<bridge>"
       case ACCESSOR      => "<accessor>"
 
diff --git a/src/compiler/scala/tools/nsc/symtab/InfoTransformers.scala b/src/compiler/scala/tools/nsc/symtab/InfoTransformers.scala
index 87f4ba7b12..bf01d4419a 100644
--- a/src/compiler/scala/tools/nsc/symtab/InfoTransformers.scala
+++ b/src/compiler/scala/tools/nsc/symtab/InfoTransformers.scala
@@ -5,7 +5,7 @@
 // $Id$
 package scala.tools.nsc.symtab;
 
-mixin class InfoTransformers requires SymbolTable {
+trait InfoTransformers requires SymbolTable {
 
   abstract class InfoTransformer {
     var prev: InfoTransformer = this;
diff --git a/src/compiler/scala/tools/nsc/symtab/Scopes.scala b/src/compiler/scala/tools/nsc/symtab/Scopes.scala
index 921d9f9cc0..a0f577c9a5 100644
--- a/src/compiler/scala/tools/nsc/symtab/Scopes.scala
+++ b/src/compiler/scala/tools/nsc/symtab/Scopes.scala
@@ -5,7 +5,7 @@
 // $Id$
 package scala.tools.nsc.symtab;
 
-mixin class Scopes requires SymbolTable {
+trait Scopes requires SymbolTable {
 
   class ScopeEntry(val sym: Symbol, val owner: Scope) {
 
diff --git a/src/compiler/scala/tools/nsc/symtab/StdNames.scala b/src/compiler/scala/tools/nsc/symtab/StdNames.scala
index 3bf7478a49..17f94dee33 100644
--- a/src/compiler/scala/tools/nsc/symtab/StdNames.scala
+++ b/src/compiler/scala/tools/nsc/symtab/StdNames.scala
@@ -7,7 +7,7 @@ package scala.tools.nsc.symtab;
 
 import scala.tools.nsc.util.NameTransformer;
 
-mixin class StdNames requires SymbolTable {
+trait StdNames requires SymbolTable {
 
   object nme {
 
diff --git a/src/compiler/scala/tools/nsc/symtab/Symbols.scala b/src/compiler/scala/tools/nsc/symtab/Symbols.scala
index ea85974721..a327a0e053 100644
--- a/src/compiler/scala/tools/nsc/symtab/Symbols.scala
+++ b/src/compiler/scala/tools/nsc/symtab/Symbols.scala
@@ -10,7 +10,7 @@ import scala.tools.util.AbstractFile;
 import scala.tools.nsc.util.{Position, SourceFile};
 import Flags._;
 
-mixin class Symbols requires SymbolTable {
+trait Symbols requires SymbolTable {
   import definitions._;
 
   private var ids = 0;
@@ -174,7 +174,7 @@ mixin class Symbols requires SymbolTable {
     final def isThisSym = isTerm && name == nme.this_;
     final def isThisSkolem = isTerm && deSkolemize != this;
     final def isError = hasFlag(IS_ERROR);
-    final def isMixin = isClass & hasFlag(MIXIN);
+    final def isTrait = isClass & hasFlag(TRAIT);
     final def isAliasType = isType && !isClass && !hasFlag(DEFERRED);
     final def isAbstractType = isType && !isClass && hasFlag(DEFERRED);
     final def isTypeParameterOrSkolem = isType && hasFlag(PARAM);
@@ -202,11 +202,11 @@ mixin class Symbols requires SymbolTable {
     final def isImplClass: boolean = isClass && hasFlag(IMPLCLASS);
 
     final def needsImplClass: boolean =
-      isMixin && (!hasFlag(INTERFACE) || hasFlag(lateINTERFACE)) && !isImplClass;
+      isTrait && (!hasFlag(INTERFACE) || hasFlag(lateINTERFACE)) && !isImplClass;
 
     final def isImplOnly: boolean = (
       hasFlag(PRIVATE) ||
-      (owner.isImplClass || owner.isMixin) &&
+      (owner.isImplClass || owner.isTrait) &&
       (hasFlag(notPRIVATE | LIFTED) && !hasFlag(ACCESSOR | SUPERACCESSOR) ||
        isConstructor)
     );
@@ -532,7 +532,7 @@ mixin class Symbols requires SymbolTable {
 
     /** The primary constructor of a class */
     def primaryConstructor: Symbol = {
-      val c = info.decl(if (isMixin || isImplClass) nme.MIXIN_CONSTRUCTOR else nme.CONSTRUCTOR);
+      val c = info.decl(if (isTrait || isImplClass) nme.MIXIN_CONSTRUCTOR else nme.CONSTRUCTOR);
       if (c hasFlag OVERLOADED) c.alternatives.head else c
     }
 
@@ -709,7 +709,8 @@ mixin class Symbols requires SymbolTable {
 
     /** String representation of symbol's definition key word */
     final def keyString: String =
-      if (isMixin && hasFlag(JAVA)) "interface"
+      if (isTrait && hasFlag(JAVA)) "interface"
+      else if (isTrait) "trait"
       else if (isClass) "class"
       else if (isType && !hasFlag(PARAM)) "type"
       else if (isVariable) "var"
@@ -726,6 +727,7 @@ mixin class Symbols requires SymbolTable {
       else if (isAnonymousClass) "<template>"
       else if (isRefinementClass) ""
       else if (isModuleClass) "singleton class"
+      else if (isTrait) "trait"
       else if (isClass) "class"
       else if (isType) "type"
       else if (isVariable) "variable"
diff --git a/src/compiler/scala/tools/nsc/symtab/Types.scala b/src/compiler/scala/tools/nsc/symtab/Types.scala
index 2b4be691c9..2ddb95018c 100644
--- a/src/compiler/scala/tools/nsc/symtab/Types.scala
+++ b/src/compiler/scala/tools/nsc/symtab/Types.scala
@@ -30,7 +30,7 @@ import Flags._;
   case TypeVar(_, _) =>
 */
 
-mixin class Types requires SymbolTable {
+trait Types requires SymbolTable {
   import definitions._;
 
   //statistics
@@ -425,7 +425,7 @@ mixin class Types requires SymbolTable {
 
 // Subclasses ------------------------------------------------------------
 
-  mixin class UniqueType {
+  trait UniqueType {
     private val hashcode = { val h = super.hashCode(); if (h < 0) -h else h }
     override def hashCode() = hashcode;
   }
diff --git a/src/compiler/scala/tools/nsc/symtab/classfile/ClassfileParser.scala b/src/compiler/scala/tools/nsc/symtab/classfile/ClassfileParser.scala
index 29360f3ab1..4b7fe373c2 100644
--- a/src/compiler/scala/tools/nsc/symtab/classfile/ClassfileParser.scala
+++ b/src/compiler/scala/tools/nsc/symtab/classfile/ClassfileParser.scala
@@ -604,7 +604,7 @@ abstract class ClassfileParser {
     if ((flags & JAVA_ACC_FINAL) != 0)
       res = res | FINAL;
     if ((flags & JAVA_ACC_INTERFACE) != 0)
-      res = res | MIXIN | INTERFACE | ABSTRACT;
+      res = res | TRAIT | INTERFACE | ABSTRACT;
     if ((flags & JAVA_ACC_SYNTHETIC) != 0)
       res = res | SYNTHETIC;
     if ((flags & JAVA_ACC_STATIC) != 0)
diff --git a/src/compiler/scala/tools/nsc/transform/AddInterfaces.scala b/src/compiler/scala/tools/nsc/transform/AddInterfaces.scala
index e6110d3976..1e4be38767 100644
--- a/src/compiler/scala/tools/nsc/transform/AddInterfaces.scala
+++ b/src/compiler/scala/tools/nsc/transform/AddInterfaces.scala
@@ -115,7 +115,7 @@ abstract class AddInterfaces extends InfoTransform {
       val parents1 =
         if (parents.isEmpty) List()
         else {
-          assert(!parents.head.symbol.isMixin || clazz == RepeatedParamClass, clazz);
+          assert(!parents.head.symbol.isTrait || clazz == RepeatedParamClass, clazz);
           if (clazz hasFlag INTERFACE) erasedTypeRef(ObjectClass) :: parents.tail
           else if (clazz.isImplClass || clazz == ArrayClass) parents
 	  else parents map mixinToImplClass
diff --git a/src/compiler/scala/tools/nsc/transform/Erasure.scala b/src/compiler/scala/tools/nsc/transform/Erasure.scala
index 68dfc794f4..ea474a68bb 100644
--- a/src/compiler/scala/tools/nsc/transform/Erasure.scala
+++ b/src/compiler/scala/tools/nsc/transform/Erasure.scala
@@ -529,7 +529,7 @@ abstract class Erasure extends AddInterfaces with typechecker.Analyzer {
 */
 
     def addBridges(stats: List[Tree], base: Symbol): List[Tree] =
-      if (base.isMixin) stats
+      if (base.isTrait) stats
       else {
         val bridges = bridgeDefs(base);
         if (bridges.isEmpty) stats else stats ::: bridges
diff --git a/src/compiler/scala/tools/nsc/transform/ExplicitOuter.scala b/src/compiler/scala/tools/nsc/transform/ExplicitOuter.scala
index bb9b34d177..4f71be7b62 100644
--- a/src/compiler/scala/tools/nsc/transform/ExplicitOuter.scala
+++ b/src/compiler/scala/tools/nsc/transform/ExplicitOuter.scala
@@ -39,9 +39,9 @@ abstract class ExplicitOuter extends InfoTransform {
   def transformInfo(sym: Symbol, tp: Type): Type = tp match {
     case MethodType(formals, restpe) =>
       //todo: needed?
-      if (sym.owner.isMixin && (sym hasFlag SUPERACCESSOR))
+      if (sym.owner.isTrait && (sym hasFlag SUPERACCESSOR))
         sym.makeNotPrivate(sym.owner);
-      if (sym.owner.isMixin && (sym hasFlag PROTECTED)) sym setFlag notPROTECTED;
+      if (sym.owner.isTrait && (sym hasFlag PROTECTED)) sym setFlag notPROTECTED;
       if (sym.isConstructor && !isStatic(sym.owner))
 	MethodType(formals ::: List(outerClass(sym.owner).toInterface.thisType), restpe)
       else tp;
@@ -51,7 +51,7 @@ abstract class ExplicitOuter extends InfoTransform {
 	if (!isStatic(clazz)) {
 	  decls1 = new Scope(decls1.toList);
 	  val outerAcc = clazz.newMethod(clazz.pos, nme.OUTER);
-	  if (clazz.isMixin || (decls.toList exists (.isClass)))
+	  if (clazz.isTrait || (decls.toList exists (.isClass)))
             outerAcc.expandName(clazz);
 	  decls1 enter (
 	    outerAcc setFlag (PARAMACCESSOR | ACCESSOR | STABLE)
@@ -60,7 +60,7 @@ abstract class ExplicitOuter extends InfoTransform {
 	    setFlag (LOCAL | PRIVATE | PARAMACCESSOR | (outerAcc getFlag EXPANDEDNAME))
 	    setInfo outerClass(clazz).thisType);
 	}
-	if (clazz.isMixin) {
+	if (clazz.isTrait) {
 	  decls1 = new Scope(decls1.toList);
 	  decls1 enter makeMixinConstructor(clazz);
 	}
@@ -258,7 +258,7 @@ abstract class ExplicitOuter extends InfoTransform {
 	    if (!(currentOwner hasFlag INTERFACE) || (currentOwner hasFlag lateINTERFACE)) {
 	      if (!isStatic(currentOwner))
 		decls1 = decls1 ::: outerDefs(currentOwner); // (1)
-	      if (currentOwner.isMixin)
+	      if (currentOwner.isTrait)
 		decls1 = decls1 ::: List(mixinConstructorDef(currentOwner)) // (2)
 	    }
 	    localTyper = savedLocalTyper;
@@ -327,7 +327,7 @@ abstract class ExplicitOuter extends InfoTransform {
 	val tree1 = super.transform(tree);
 	tree1 match {
           case DefDef(_, _, _, _, _, _) =>
-            if (sym.owner.isMixin && (sym hasFlag (ACCESSOR | SUPERACCESSOR)))
+            if (sym.owner.isTrait && (sym hasFlag (ACCESSOR | SUPERACCESSOR)))
               sym.makeNotPrivate(sym.owner); //(2)
             tree1
 	  case Select(qual, name) =>
diff --git a/src/compiler/scala/tools/nsc/transform/Mixin.scala b/src/compiler/scala/tools/nsc/transform/Mixin.scala
index 8ad57a5bad..0802e00359 100644
--- a/src/compiler/scala/tools/nsc/transform/Mixin.scala
+++ b/src/compiler/scala/tools/nsc/transform/Mixin.scala
@@ -101,7 +101,7 @@ abstract class Mixin extends InfoTransform {
 
   def addMixedinMembers(clazz: Symbol): unit = {
     if (!(clazz hasFlag MIXEDIN) && (clazz != ObjectClass)) {
-      assert(!clazz.isMixin, clazz);
+      assert(!clazz.isTrait, clazz);
       clazz setFlag MIXEDIN;
       assert(!clazz.info.parents.isEmpty, clazz);
       val superclazz = clazz.info.parents.head.symbol;
@@ -216,7 +216,7 @@ abstract class Mixin extends InfoTransform {
         case Template(parents, body) =>
 	  localTyper = erasure.newTyper(rootContext.make(tree, currentOwner));
 	  atPhase(phase.next)(currentOwner.owner.info);//needed?
-          if (!currentOwner.isMixin) addMixedinMembers(currentOwner)
+          if (!currentOwner.isTrait) addMixedinMembers(currentOwner)
           else if (currentOwner hasFlag lateINTERFACE) addLateInterfaceMembers(currentOwner);
 	  tree
         case DefDef(mods, name, tparams, List(vparams), tpt, rhs) if currentOwner.isImplClass =>
@@ -300,7 +300,7 @@ abstract class Mixin extends InfoTransform {
 	if (sym hasFlag MIXEDIN) {
           if (clazz hasFlag lateINTERFACE) {
 	    addDefDef(sym, vparamss => EmptyTree)
-	  } else if (!clazz.isMixin) {
+	  } else if (!clazz.isTrait) {
 	    if (sym hasFlag ACCESSOR) {
               addDefDef(sym, vparams => {
 		val accessedRef = sym.tpe match {
@@ -325,7 +325,7 @@ abstract class Mixin extends InfoTransform {
 	}
       }
       val stats1 = add(stats, newDefs.toList);
-      if (clazz.isMixin) stats1 else stats1 map completeSuperAccessor;
+      if (clazz.isTrait) stats1 else stats1 map completeSuperAccessor;
     }
 
     private def postTransform(tree: Tree): Tree = {
diff --git a/src/compiler/scala/tools/nsc/typechecker/Analyzer.scala b/src/compiler/scala/tools/nsc/typechecker/Analyzer.scala
index ed7382dc8a..ed76cb6b91 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Analyzer.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Analyzer.scala
@@ -7,7 +7,7 @@ package scala.tools.nsc.typechecker;
 
 /** The main attribution phase.
  */
-mixin class Analyzer
+trait Analyzer
 	 extends AnyRef
             with Contexts
     	    with Namers
diff --git a/src/compiler/scala/tools/nsc/typechecker/Codification.scala b/src/compiler/scala/tools/nsc/typechecker/Codification.scala
index b7383fce5b..6a802d7c31 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Codification.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Codification.scala
@@ -11,7 +11,7 @@ import scala.collection.immutable.ListMap;
 import scala.collection.mutable.ListBuffer;
 import scala.tools.nsc.util.FreshNameCreator;
 
-mixin class Codification requires Analyzer {
+trait Codification requires Analyzer {
 
   import global._;
 
diff --git a/src/compiler/scala/tools/nsc/typechecker/Contexts.scala b/src/compiler/scala/tools/nsc/typechecker/Contexts.scala
index ba35ebbb4b..0da9ee6177 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Contexts.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Contexts.scala
@@ -8,7 +8,7 @@ package scala.tools.nsc.typechecker;
 import symtab.Flags._;
 import scala.tools.nsc.util.Position;
 
-mixin class Contexts requires Analyzer {
+trait Contexts requires Analyzer {
   import global._;
 
   val NoContext = new Context {
diff --git a/src/compiler/scala/tools/nsc/typechecker/EtaExpansion.scala b/src/compiler/scala/tools/nsc/typechecker/EtaExpansion.scala
index 28bbff53c2..de70ccf5a7 100644
--- a/src/compiler/scala/tools/nsc/typechecker/EtaExpansion.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/EtaExpansion.scala
@@ -8,7 +8,7 @@ package scala.tools.nsc.typechecker;
 import scala.collection.mutable.ListBuffer;
 import symtab.Flags._;
 
-mixin class EtaExpansion requires Analyzer {
+trait EtaExpansion requires Analyzer {
 
   import global._;
   import posAssigner.atPos;
diff --git a/src/compiler/scala/tools/nsc/typechecker/Infer.scala b/src/compiler/scala/tools/nsc/typechecker/Infer.scala
index 467b7b7465..1004b4b67d 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Infer.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Infer.scala
@@ -8,7 +8,7 @@ package scala.tools.nsc.typechecker;
 import scala.collection.mutable.ListBuffer;
 import symtab.Flags._;
 
-mixin class Infer requires Analyzer {
+trait Infer requires Analyzer {
   import global._;
   import definitions._;
   import posAssigner.atPos;
diff --git a/src/compiler/scala/tools/nsc/typechecker/Namers.scala b/src/compiler/scala/tools/nsc/typechecker/Namers.scala
index 8668afae91..1b191da676 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Namers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Namers.scala
@@ -10,7 +10,7 @@ import symtab.Flags;
 import symtab.Flags._;
 
 /** Methods to create symbols and to enter them into scopes. */
-mixin class Namers requires Analyzer {
+trait Namers requires Analyzer {
   import global._;
   import definitions._;
 
@@ -544,15 +544,13 @@ mixin class Namers requires Analyzer {
 	      Flags.flagsToString(flag1) + " and " + Flags.flagsToString(flag2));
       if (sym.hasFlag(IMPLICIT) && !sym.isTerm)
 	context.error(sym.pos, "`implicit' modifier can be used only for values, variables and methods");
-      if (sym.hasFlag(MIXIN) && !sym.isClass)
-	context.error(sym.pos, "`mixin' modifier can be used only for classes");
       if (sym.hasFlag(ABSTRACT) && !sym.isClass)
 	context.error(sym.pos, "`abstract' modifier can be used only for classes; " +
 	  "\nit should be omitted for abstract members");
       if (sym.hasFlag(OVERRIDE | ABSOVERRIDE) && sym.isClass)
 	context.error(sym.pos, "`override' modifier not allowed for classes");
-      if (sym.hasFlag(ABSOVERRIDE) && !sym.owner.isMixin)
-	context.error(sym.pos, "`abstract override' modifier only allowed for members of mixin classes");
+      if (sym.hasFlag(ABSOVERRIDE) && !sym.owner.isTrait)
+	context.error(sym.pos, "`abstract override' modifier only allowed for members of traits");
       if (sym.info.symbol == FunctionClass(0) &&
 	  sym.isValueParameter && sym.owner.isClass && sym.owner.hasFlag(CASE))
 	context.error(sym.pos, "pass-by-name arguments not allowed for case class parameters");
diff --git a/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala b/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala
index 5af2caf977..41cfdf30bf 100644
--- a/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala
@@ -230,7 +230,7 @@ abstract class RefChecks extends InfoTransform {
 	}
 */
       // 2. Check that only abstract classes have deferred members
-      if (clazz.isClass && !clazz.isMixin) {
+      if (clazz.isClass && !clazz.isTrait) {
 	def abstractClassError(mustBeMixin: boolean, msg: String): unit = {
 	  unit.error(clazz.pos,
 	    (if (clazz.isAnonymousClass || clazz.isModuleClass) "object creation impossible"
@@ -464,12 +464,12 @@ abstract class RefChecks extends InfoTransform {
           val ddef =
 	    atPhase(phase.next) {
 	      localTyper.typed {
-                if (sym.owner.isMixin) newModuleAccessDcl(sym)
+                if (sym.owner.isTrait) newModuleAccessDcl(sym)
                 else newModuleAccessDef(sym, vdef.symbol)
               }
             }
 
-          if (sym.owner.isMixin) transformTrees(List(cdef, ddef))
+          if (sym.owner.isTrait) transformTrees(List(cdef, ddef))
           else transformTrees(List(cdef, vdef, ddef))
 	}
 
@@ -597,7 +597,7 @@ abstract class RefChecks extends InfoTransform {
 		  unit.error(tree.pos, "symbol accessed from super may not be abstract");
               }
               //System.out.println("super: " + tree + " in " + base);//DEBUG
-              if (base.isMixin && sym.isTerm && mix == nme.EMPTY.toTypeName) {
+              if (base.isTrait && sym.isTerm && mix == nme.EMPTY.toTypeName) {
                 val superAccName = nme.superName(sym.name);
 	        val superAcc = base.info.decl(superAccName) suchThat (.alias.==(sym));
 	        assert(superAcc != NoSymbol, "" + sym + " " + base + " " + superAccName);//debug
diff --git a/src/compiler/scala/tools/nsc/typechecker/SuperAccessors.scala b/src/compiler/scala/tools/nsc/typechecker/SuperAccessors.scala
index 7e0562d633..4eb38f349b 100644
--- a/src/compiler/scala/tools/nsc/typechecker/SuperAccessors.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/SuperAccessors.scala
@@ -46,7 +46,7 @@ abstract class SuperAccessors extends transform.Transform {
       case Select(sup @ Super(_, mix), name) =>
 	val clazz = sup.symbol;
 	if (tree.isTerm && mix == nme.EMPTY.toTypeName &&
-	    (clazz.isMixin || clazz != currentOwner.enclClass || !validCurrentOwner)) {
+	    (clazz.isTrait || clazz != currentOwner.enclClass || !validCurrentOwner)) {
 	  val supername = nme.superName(tree.symbol.name);
 	  var superAcc = clazz.info.decl(supername).suchThat(.alias.==(tree.symbol));
 	  if (superAcc == NoSymbol) {
diff --git a/src/compiler/scala/tools/nsc/typechecker/SyntheticMethods.scala b/src/compiler/scala/tools/nsc/typechecker/SyntheticMethods.scala
index b2268ff239..306dad37c6 100644
--- a/src/compiler/scala/tools/nsc/typechecker/SyntheticMethods.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/SyntheticMethods.scala
@@ -18,7 +18,7 @@ import scala.collection.mutable.ListBuffer;
  *       unless they are defined in the class or a baseclass
  *       different from java.lang.Object
 */
-mixin class SyntheticMethods requires Analyzer {
+trait SyntheticMethods requires Analyzer {
   import global._;                  // the global environment
   import definitions._;             // standard classes and methods
   import typer.{typed};             // methods to type trees
diff --git a/src/compiler/scala/tools/nsc/typechecker/Typers.scala b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
index 10c96ac749..4482480496 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Typers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
@@ -11,7 +11,7 @@ import scala.tools.nsc.util.Position
 import scala.collection.mutable.{HashMap, ListBuffer}
 
 /** Methods to create symbols and to enter them into scopes. */
-mixin class Typers requires Analyzer {
+trait Typers requires Analyzer {
   import global._
   import definitions._
   import posAssigner.atPos
@@ -510,8 +510,8 @@ mixin class Typers requires Analyzer {
       else {
 	var supertpt = typedTypeConstructor(templ.parents.head)
 	var mixins = templ.parents.tail map typedType
-	// If first parent is a mixin class, make it first mixin and add its superclass as first parent
-	while (supertpt.tpe.symbol != null && supertpt.tpe.symbol.initialize.isMixin) {
+	// If first parent is a trait, make it first mixin and add its superclass as first parent
+	while (supertpt.tpe.symbol != null && supertpt.tpe.symbol.initialize.isTrait) {
 	  mixins = typedType(supertpt) :: mixins
 	  supertpt = TypeTree(supertpt.tpe.parents.head) setOriginal supertpt /* setPos supertpt.pos */
 	}
@@ -558,16 +558,16 @@ mixin class Typers requires Analyzer {
 	  if (!psym.isClass)
 	    error(parent.pos, "class type expected")
 	  else if (psym != superclazz)
-            if (psym.isMixin) {
+            if (psym.isTrait) {
               val ps = psym.info.parents
               if (!ps.isEmpty && !superclazz.isSubClass(ps.head.symbol))
                 error(parent.pos, "illegal inheritance; super"+superclazz+
                       "\n is not a subclass of the super"+ps.head.symbol+
                       "\n of the mixin " + psym);
             } else if (settings.migrate.value)
-              error(parent.pos, migrateMsg+psym+" needs to be a declared as a mixin class")
+              error(parent.pos, migrateMsg+psym+" needs to be a declared as a trait")
             else
-	      error(parent.pos, ""+psym+" is not declared to be a mixin class")
+	      error(parent.pos, ""+psym+" is not declared to be a trait")
 	  else if (psym.hasFlag(FINAL))
 	    error(parent.pos, "illegal inheritance from final class")
 	  else if (!phase.erasedTypes && psym.isSealed &&
@@ -1295,7 +1295,6 @@ mixin class Typers requires Analyzer {
             val rhs1 = typed(rhs, lhs1.tpe)
             copy.Assign(tree, lhs1, rhs1) setType UnitClass.tpe
           } else {
-            System.out.println(""+lhs1+" "+varsym+" "+varsym.isValue+" "+flagsToString(varsym.flags));//debug
             if (!lhs1.tpe.isError) error(tree.pos, "assignment to non-variable ")
             setError(tree)
           }
diff --git a/src/compiler/scala/tools/nsc/typechecker/Variances.scala b/src/compiler/scala/tools/nsc/typechecker/Variances.scala
index 2992f92d3c..2bdb019374 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Variances.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Variances.scala
@@ -9,7 +9,7 @@ import symtab.Flags._;
 
 /** Variances form a lattice, 0 <= COVARIANT <= Variances, 0 <= CONTRAVARIANT <= VARIANCES
  */
-mixin class Variances {
+trait Variances {
 
   val global: Global;
   import global._;
diff --git a/src/library/scala/Application.scala b/src/library/scala/Application.scala
index 8d5327e8be..2437a5ffaa 100644
--- a/src/library/scala/Application.scala
+++ b/src/library/scala/Application.scala
@@ -36,7 +36,7 @@ package scala;
  *  @version 1.0, 10/09/03
  */
 
-mixin class Application {
+trait Application {
 
     /** The time when execution of this program started.
      */
diff --git a/src/library/scala/BufferedIterator.scala b/src/library/scala/BufferedIterator.scala
index 0675f22167..7a5d26d281 100644
--- a/src/library/scala/BufferedIterator.scala
+++ b/src/library/scala/BufferedIterator.scala
@@ -12,13 +12,13 @@
 package scala;
 
 
-/** Buffered iterators are iterators which allow to inspect the next
+/** Buffered iterators are iterators which llow to inspect the next
  *  element without discarding it.
  *
  *  @author  Martin Odersky
  *  @version 1.0, 16/07/2003
  */
-mixin class BufferedIterator[+A] extends Iterator[A] {
+trait BufferedIterator[+A] extends Iterator[A] {
 
     /** Checks what the next available element is.
      *
diff --git a/src/library/scala/CaseClass.scala b/src/library/scala/CaseClass.scala
index 91b290956e..d50220f737 100644
--- a/src/library/scala/CaseClass.scala
+++ b/src/library/scala/CaseClass.scala
@@ -16,7 +16,7 @@ package scala;
  *
  *  @author  Burak Emir
  */
-mixin class CaseClass extends AnyRef {
+trait CaseClass extends AnyRef {
 
   /** for a case class A(x_0,...,x_(k-1)), returns x_i for 0 &lt;= i &lt; k,
   **  null otherwise
diff --git a/src/library/scala/CountedIterator.scala b/src/library/scala/CountedIterator.scala
index bce9fd45fe..cf45174e17 100644
--- a/src/library/scala/CountedIterator.scala
+++ b/src/library/scala/CountedIterator.scala
@@ -18,7 +18,7 @@ package scala;
  *  @author  Martin Odersky
  *  @version 1.0, 16/07/2003
  */
-mixin class CountedIterator[+A] extends Iterator[A] {
+trait CountedIterator[+A] extends Iterator[A] {
 
   /** counts the elements in this iterator; counts start at 0
    */
diff --git a/src/library/scala/Function0.scala b/src/library/scala/Function0.scala
index 7309ed403c..e7d2da57f4 100644
--- a/src/library/scala/Function0.scala
+++ b/src/library/scala/Function0.scala
@@ -15,7 +15,7 @@ package scala;
 /**
  * Function with no parameters
  */
-mixin class Function0[+R] extends AnyRef {
+trait Function0[+R] extends AnyRef {
   def apply(): R;
   override def toString() = "<function>";
 }
diff --git a/src/library/scala/Function1.scala b/src/library/scala/Function1.scala
index a5e19bb2fa..f928596332 100644
--- a/src/library/scala/Function1.scala
+++ b/src/library/scala/Function1.scala
@@ -15,7 +15,7 @@ package scala;
 /**
  * Function with 1 parameter
  */
-mixin class Function1[-T0, +R] extends AnyRef {
+trait Function1[-T0, +R] extends AnyRef {
   def apply(v0: T0): R;
   override def toString() = "<function>";
 }
diff --git a/src/library/scala/Function2.scala b/src/library/scala/Function2.scala
index e58173d6b3..bea1a9a951 100644
--- a/src/library/scala/Function2.scala
+++ b/src/library/scala/Function2.scala
@@ -15,7 +15,7 @@ package scala;
 /**
  * Function with 2 parameters
  */
-mixin class Function2[-T0, -T1, +R] extends AnyRef {
+trait Function2[-T0, -T1, +R] extends AnyRef {
   def apply(v0: T0, v1: T1): R;
   override def toString() = "<function>";
 }
diff --git a/src/library/scala/Function3.scala b/src/library/scala/Function3.scala
index 09d8633f7f..d161362d03 100644
--- a/src/library/scala/Function3.scala
+++ b/src/library/scala/Function3.scala
@@ -15,7 +15,7 @@ package scala;
 /**
  * Function with 3 parameters
  */
-mixin class Function3[-T0, -T1, -T2, +R] extends AnyRef {
+trait Function3[-T0, -T1, -T2, +R] extends AnyRef {
   def apply(v0: T0, v1: T1, v2: T2): R;
   override def toString() = "<function>";
 }
diff --git a/src/library/scala/Function4.scala b/src/library/scala/Function4.scala
index 3bae61ead6..7ddbed0031 100644
--- a/src/library/scala/Function4.scala
+++ b/src/library/scala/Function4.scala
@@ -15,7 +15,7 @@ package scala;
 /**
  * Function with 4 parameters
  */
-mixin class Function4[-T0, -T1, -T2, -T3, +R] extends AnyRef {
+trait Function4[-T0, -T1, -T2, -T3, +R] extends AnyRef {
   def apply(v0: T0, v1: T1, v2: T2, v3: T3): R;
   override def toString() = "<function>";
 }
diff --git a/src/library/scala/Function5.scala b/src/library/scala/Function5.scala
index 7bebfa5d5b..74fe7d1ca1 100644
--- a/src/library/scala/Function5.scala
+++ b/src/library/scala/Function5.scala
@@ -15,7 +15,7 @@ package scala;
 /**
  * Function with 5 parameters
  */
-mixin class Function5[-T0, -T1, -T2, -T3, -T4, +R] extends AnyRef {
+trait Function5[-T0, -T1, -T2, -T3, -T4, +R] extends AnyRef {
   def apply(v0: T0, v1: T1, v2: T2, v3: T3, v4: T4): R;
   override def toString() = "<function>";
 }
diff --git a/src/library/scala/Function6.scala b/src/library/scala/Function6.scala
index d9709a0e46..a46f17bb61 100644
--- a/src/library/scala/Function6.scala
+++ b/src/library/scala/Function6.scala
@@ -15,7 +15,7 @@ package scala;
 /**
  * Function with 6 parameters
  */
-mixin class Function6[-T0, -T1, -T2, -T3, -T4, -T5, +R] extends AnyRef {
+trait Function6[-T0, -T1, -T2, -T3, -T4, -T5, +R] extends AnyRef {
   def apply(v0: T0, v1: T1, v2: T2, v3: T3, v4: T4, v5: T5): R;
   override def toString() = "<function>";
 }
diff --git a/src/library/scala/Function7.scala b/src/library/scala/Function7.scala
index 0398c349ac..95bdb39275 100644
--- a/src/library/scala/Function7.scala
+++ b/src/library/scala/Function7.scala
@@ -15,7 +15,7 @@ package scala;
 /**
  * Function with 7 parameters
  */
-mixin class Function7[-T0, -T1, -T2, -T3, -T4, -T5, -T6, +R] extends AnyRef {
+trait Function7[-T0, -T1, -T2, -T3, -T4, -T5, -T6, +R] extends AnyRef {
   def apply(v0: T0, v1: T1, v2: T2, v3: T3, v4: T4, v5: T5, v6: T6): R;
   override def toString() = "<function>";
 }
diff --git a/src/library/scala/Function8.scala b/src/library/scala/Function8.scala
index 0630402a3e..e0b87f00e2 100644
--- a/src/library/scala/Function8.scala
+++ b/src/library/scala/Function8.scala
@@ -15,7 +15,7 @@ package scala;
 /**
  * Function with 8 parameters
  */
-mixin class Function8[-T0, -T1, -T2, -T3, -T4, -T5, -T6, -T7, +R] extends AnyRef {
+trait Function8[-T0, -T1, -T2, -T3, -T4, -T5, -T6, -T7, +R] extends AnyRef {
   def apply(v0: T0, v1: T1, v2: T2, v3: T3, v4: T4, v5: T5, v6: T6, v7: T7): R;
   override def toString() = "<function>";
 }
diff --git a/src/library/scala/Function9.scala b/src/library/scala/Function9.scala
index 8e82ded993..87761c6f59 100644
--- a/src/library/scala/Function9.scala
+++ b/src/library/scala/Function9.scala
@@ -15,7 +15,7 @@ package scala;
 /**
  * Function with 9 parameters
  */
-mixin class Function9[-T0, -T1, -T2, -T3, -T4, -T5, -T6, -T7, -T8, +R] extends AnyRef {
+trait Function9[-T0, -T1, -T2, -T3, -T4, -T5, -T6, -T7, -T8, +R] extends AnyRef {
   def apply(v0: T0, v1: T1, v2: T2, v3: T3, v4: T4, v5: T5, v6: T6, v7: T7, v8: T8): R;
   override def toString() = "<function>";
 }
diff --git a/src/library/scala/Iterable.scala b/src/library/scala/Iterable.scala
index 4700649a63..581b39201a 100644
--- a/src/library/scala/Iterable.scala
+++ b/src/library/scala/Iterable.scala
@@ -65,7 +65,7 @@ object Iterable {
  *  @author  Matthias Zenger
  *  @version 1.1, 04/02/2004
  */
-mixin class Iterable[+A] {
+trait Iterable[+A] {
 
     /** Creates a new iterator over all elements contained in this
      *  object.
diff --git a/src/library/scala/IterableProxy.scala b/src/library/scala/IterableProxy.scala
index ed45c58f5c..0b8ddc88df 100644
--- a/src/library/scala/IterableProxy.scala
+++ b/src/library/scala/IterableProxy.scala
@@ -18,7 +18,7 @@ package scala;
  *  @author  Matthias Zenger
  *  @version 1.0, 26/04/2004
  */
-mixin class IterableProxy[+A] extends Iterable[A] with Proxy {
+trait IterableProxy[+A] extends Iterable[A] with Proxy {
 
     def self: Iterable[A];
 
diff --git a/src/library/scala/Iterator.scala b/src/library/scala/Iterator.scala
index ded761dcfc..ac394b2ce9 100644
--- a/src/library/scala/Iterator.scala
+++ b/src/library/scala/Iterator.scala
@@ -173,7 +173,7 @@ object Iterator {
  *  @author  Matthias Zenger
  *  @version 1.2, 15/03/2004
  */
-mixin class Iterator[+A] {
+trait Iterator[+A] {
 
   /** Does this iterator provide another element?
    */
diff --git a/src/library/scala/List.scala b/src/library/scala/List.scala
index 3050fa9634..c9f5789310 100644
--- a/src/library/scala/List.scala
+++ b/src/library/scala/List.scala
@@ -1057,10 +1057,10 @@ sealed abstract class List[+a] extends Seq[a] {
  *  @version 1.0, 15/07/2003
  */
 [SerialVersionUID(0 - 8256821097970055419L)]
-case object Nil extends List[All] {
+case object Nil extends List[Bottom] {
   def isEmpty = true;
   def head: All = error("head of empty list");
-  def tail: List[All] = error("tail of empty list");
+  def tail: List[Bottom] = error("tail of empty list");
 }
 
 /** A non empty list characterized by a head and a tail.
diff --git a/src/library/scala/MatchError.scala b/src/library/scala/MatchError.scala
index 8607334e41..37fe5a00e9 100644
--- a/src/library/scala/MatchError.scala
+++ b/src/library/scala/MatchError.scala
@@ -11,6 +11,7 @@
 
 package scala;
 
+import Predef._
 
 /** This class implements errors which are thrown whenever an
  *  object doesn't match any pattern of a pattern matching
@@ -23,7 +24,7 @@ package scala;
 object MatchError {
 
   // todo: change pattern matcher so that dummy type parameter T can be removed.
-  def fail[T](source: String, line: Int): All = throw new MatchError(source, line);
+  def fail[T](source: String, line: Int): Bottom = throw new MatchError(source, line);
 
   def report(source: String, line: Int, obj: Any) =
     try {
diff --git a/src/library/scala/None.scala b/src/library/scala/None.scala
deleted file mode 100644
index 00e9cdaf2f..0000000000
--- a/src/library/scala/None.scala
+++ /dev/null
@@ -1,20 +0,0 @@
-/*                     __                                               *\
-**     ________ ___   / /  ___     Scala API                            **
-**    / __/ __// _ | / /  / _ |    (c) 2002-2006, LAMP/EPFL             **
-**  __\ \/ /__/ __ |/ /__/ __ |                                         **
-** /____/\___/_/ |_/____/_/ | |                                         **
-**                          |/                                          **
-\*                                                                      */
-
-// $Id$
-
-
-package scala;
-
-
-/** This case object represents non-existent values.
- *
- *  @author  Martin Odersky
- *  @version 1.0, 16/07/2003
- */
-case object None extends Option[All];
diff --git a/src/library/scala/Option.scala b/src/library/scala/Option.scala
index 0bd03599cf..ff93da86b0 100644
--- a/src/library/scala/Option.scala
+++ b/src/library/scala/Option.scala
@@ -11,6 +11,7 @@
 
 package scala;
 
+import Predef._
 
 /** This class represents optional values. Instances of <code>Option</code>
  *  are either instances of case class <code>Some</code> or it is case
@@ -20,7 +21,7 @@ package scala;
  *  @author  Matthias Zenger
  *  @version 1.0, 16/07/2003
  */
-abstract class Option[+A] extends Iterable[A] {
+sealed abstract class Option[+A] extends Iterable[A] {
 
   def isEmpty: Boolean = this match {
     case None => true
@@ -68,3 +69,18 @@ abstract class Option[+A] extends Iterable[A] {
   }
 
 }
+
+/** Class <code>Some[A]</code> represents existing values of type
+ *  <code>A</code>.
+ *
+ *  @author  Martin Odersky
+ *  @version 1.0, 16/07/2003
+ */
+final case class Some[+A](x: A) extends Option[A];
+
+/** This case object represents non-existent values.
+ *
+ *  @author  Martin Odersky
+ *  @version 1.0, 16/07/2003
+ */
+case object None extends Option[Bottom];
diff --git a/src/library/scala/Ordered.scala b/src/library/scala/Ordered.scala
index 2c14369575..eca26f290b 100644
--- a/src/library/scala/Ordered.scala
+++ b/src/library/scala/Ordered.scala
@@ -17,7 +17,7 @@ package scala;
  *  @author  Martin Odersky
  *  @version 1.0, 23/04/2004
  */
-mixin class Ordered[+a] {
+trait Ordered[+a] {
 
   /** Result of comparing `this' with operand `that'.
    *  returns `x' where
diff --git a/src/library/scala/PartialFunction.scala b/src/library/scala/PartialFunction.scala
index ed5d64ca1c..8af05728f1 100644
--- a/src/library/scala/PartialFunction.scala
+++ b/src/library/scala/PartialFunction.scala
@@ -20,7 +20,7 @@ package scala;
  *  @author  Martin Odersky
  *  @version 1.0, 16/07/2003
  */
-mixin class PartialFunction[-A, +B] extends AnyRef with (A => B) {
+trait PartialFunction[-A, +B] extends AnyRef with (A => B) {
 
     /** Checks if a value is contained in the functions domain.
      *
diff --git a/src/library/scala/PartiallyOrdered.scala b/src/library/scala/PartiallyOrdered.scala
index ab8c5ae997..45aa1fc58b 100644
--- a/src/library/scala/PartiallyOrdered.scala
+++ b/src/library/scala/PartiallyOrdered.scala
@@ -17,7 +17,7 @@ package scala;
  *  @author  Martin Odersky
  *  @version 1.0, 23/04/2004
  */
-mixin class PartiallyOrdered[+a] {
+trait PartiallyOrdered[+a] {
 
   /** Result of comparing `this' with operand `that'.
    *  Returns `None' if operands are not comparable.
diff --git a/src/library/scala/Predef.scala b/src/library/scala/Predef.scala
index 37acc7a764..1d082d1db3 100644
--- a/src/library/scala/Predef.scala
+++ b/src/library/scala/Predef.scala
@@ -20,6 +20,9 @@ object Predef {
 
   // aliases -------------------------------------------------------
 
+  type Bottom = All
+  type Null = AllRef
+
   type byte = scala.Byte;
   type short = scala.Short;
   type char = scala.Char;
@@ -149,11 +152,11 @@ object Predef {
 
   // errors and asserts -------------------------------------------------
 
-  def error(message: String): All = throw new Error(message);
+  def error(message: String): Bottom = throw new Error(message);
 
-  def exit: All = exit(0);
+  def exit: Bottom = exit(0);
 
-  def exit(status: Int): All = {
+  def exit(status: Int): Bottom = {
     java.lang.System.exit(status);
     throw new Throwable()
   }
diff --git a/src/library/scala/Proxy.scala b/src/library/scala/Proxy.scala
index 4ccde24a23..64e2a333f8 100644
--- a/src/library/scala/Proxy.scala
+++ b/src/library/scala/Proxy.scala
@@ -20,7 +20,7 @@ package scala;
  *  @author  Matthias Zenger
  *  @version 1.0, 26/04/2004
  */
-mixin class Proxy {
+trait Proxy {
   def self: Any;
   override def hashCode(): Int = self.hashCode();
   override def equals(y: Any): Boolean = self.equals(y);
diff --git a/src/library/scala/ScalaObject.scala b/src/library/scala/ScalaObject.scala
index 5b328704ef..7d213e33b3 100644
--- a/src/library/scala/ScalaObject.scala
+++ b/src/library/scala/ScalaObject.scala
@@ -12,7 +12,7 @@
 package scala
 
 
-mixin class ScalaObject extends AnyRef {
+trait ScalaObject extends AnyRef {
 
   /** This method is needed for optimizing pattern matching expressions
    *  which match on constructors of case classes.
diff --git a/src/library/scala/SeqProxy.scala b/src/library/scala/SeqProxy.scala
index 5c3aa26179..0828349deb 100644
--- a/src/library/scala/SeqProxy.scala
+++ b/src/library/scala/SeqProxy.scala
@@ -19,7 +19,7 @@ package scala;
  *  @author  Matthias Zenger
  *  @version 1.0, 16/07/2003
  */
-mixin class SeqProxy[+A] extends Seq[A] with IterableProxy[A] {
+trait SeqProxy[+A] extends Seq[A] with IterableProxy[A] {
 
     def self: Seq[A];
 
diff --git a/src/library/scala/Some.scala b/src/library/scala/Some.scala
deleted file mode 100644
index e8235f26e8..0000000000
--- a/src/library/scala/Some.scala
+++ /dev/null
@@ -1,21 +0,0 @@
-/*                     __                                               *\
-**     ________ ___   / /  ___     Scala API                            **
-**    / __/ __// _ | / /  / _ |    (c) 2002-2006, LAMP/EPFL             **
-**  __\ \/ /__/ __ |/ /__/ __ |                                         **
-** /____/\___/_/ |_/____/_/ | |                                         **
-**                          |/                                          **
-\*                                                                      */
-
-// $Id$
-
-
-package scala;
-
-
-/** Class <code>Option[A]</code> represents existing values of type
- *  <code>A</code>.
- *
- *  @author  Martin Odersky
- *  @version 1.0, 16/07/2003
- */
-final case class Some[+A](x: A) extends Option[A];
diff --git a/src/library/scala/Stream.scala b/src/library/scala/Stream.scala
index cfdc49f07b..d86af7392d 100644
--- a/src/library/scala/Stream.scala
+++ b/src/library/scala/Stream.scala
@@ -21,10 +21,10 @@ package scala;
  */
 object Stream {
 
-  val empty: Stream[All] = new Stream[All] {
+  val empty: Stream[Bottom] = new Stream[Bottom] {
     def isEmpty = true;
-    def head: All = error("head of empty stream");
-    def tail: Stream[All] = error("tail of empty stream");
+    def head: Bottom = error("head of empty stream");
+    def tail: Stream[Bottom] = error("tail of empty stream");
     def printElems(buf: StringBuffer, prefix: String): StringBuffer = buf;
   }
 
diff --git a/src/library/scala/collection/mutable/DoubleLinkedList.scala b/src/library/scala/collection/mutable/DoubleLinkedList.scala
index 610dc3f6e5..3f5b276aee 100644
--- a/src/library/scala/collection/mutable/DoubleLinkedList.scala
+++ b/src/library/scala/collection/mutable/DoubleLinkedList.scala
@@ -20,7 +20,7 @@ package scala.collection.mutable;
  *  @author  Matthias Zenger
  *  @version 1.0, 08/07/2003
  */
-abstract class DoubleLinkedList[A, This >: AllRef <: DoubleLinkedList[A, This]]
+abstract class DoubleLinkedList[A, This >: Null <: DoubleLinkedList[A, This]]
          requires This
          extends SingleLinkedList[A, This]
 {
diff --git a/src/library/scala/collection/mutable/SingleLinkedList.scala b/src/library/scala/collection/mutable/SingleLinkedList.scala
index 32b4690d4d..00346e83db 100644
--- a/src/library/scala/collection/mutable/SingleLinkedList.scala
+++ b/src/library/scala/collection/mutable/SingleLinkedList.scala
@@ -20,7 +20,7 @@ package scala.collection.mutable;
  *  @author  Matthias Zenger
  *  @version 1.0, 08/07/2003
  */
-abstract class SingleLinkedList[A, This >: AllRef <: SingleLinkedList[A, This]]
+abstract class SingleLinkedList[A, This >: Null <: SingleLinkedList[A, This]]
          requires This
          extends AnyRef with Seq[A]
 {
diff --git a/src/library/scala/concurrent/MailBox.scala b/src/library/scala/concurrent/MailBox.scala
index 049259a988..44418d448d 100644
--- a/src/library/scala/concurrent/MailBox.scala
+++ b/src/library/scala/concurrent/MailBox.scala
@@ -139,7 +139,7 @@ mixin class ListQueueCreator {
 /** Efficient queue module creator based on linked lists. */
 mixin class LinkedListQueueCreator {
   import scala.collection.mutable.LinkedList;
-  def queueCreate[a >: AllRef <: AnyRef]: QueueModule[a] = new QueueModule[a] {
+  def queueCreate[a >: Null <: AnyRef]: QueueModule[a] = new QueueModule[a] {
     type t = Pair[LinkedList[a], LinkedList[a]]; // fst = the list, snd = last elem
     def make: t = {
       val l = new LinkedList[a](null, null);
diff --git a/src/library/scala/dbc/datatype/CharacterString.scala b/src/library/scala/dbc/datatype/CharacterString.scala
index dae029d600..1f250475b3 100644
--- a/src/library/scala/dbc/datatype/CharacterString.scala
+++ b/src/library/scala/dbc/datatype/CharacterString.scala
@@ -15,10 +15,10 @@ package scala.dbc.datatype;
 /** A type category for all SQL types that store strings of characters. */
 abstract class CharacterString extends String {
 
-	type NativeType = java.lang.String;
-	val nativeTypeId = DataType.STRING;
+  type NativeType = java.lang.String;
+  val nativeTypeId = DataType.STRING;
 
-	/** The name of the character set in which the string is encoded. */
-	def encoding: Option[java.lang.String] = None;
+  /** The name of the character set in which the string is encoded. */
+  def encoding: Option[java.lang.String] = None;
 
 }
diff --git a/src/library/scala/runtime/ScalaRunTime.scala b/src/library/scala/runtime/ScalaRunTime.scala
index 83fa174f4e..9612f9823d 100644
--- a/src/library/scala/runtime/ScalaRunTime.scala
+++ b/src/library/scala/runtime/ScalaRunTime.scala
@@ -90,7 +90,7 @@ object ScalaRunTime {
       false
   }
 
-  //def checkDefined[T >: AllRef](x: T): T =
+  //def checkDefined[T >: Null](x: T): T =
   //  if (x == null) throw new UndefinedException else x
 
   def Seq[a](xs: a*): Seq[a] = null; // interpreted specially by new backend.
-- 
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