addressing 3 previous review comments

frog/value.dart

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /**
  * Represents a meta-value for code generation.
  */
 class Value {
   Type _type;
 
@@ skipping 563 matching lines @@
 
 
 // TODO(jimhug): rename to PrimitiveValue and refactor further
 class EvaluatedValue extends Value implements Hashable {
   /** Is this value treated as const by dart language? */
   bool isConst;
 
   EvaluatedValue(this.isConst, Type type, SourceSpan span):
     super(type, '@@@', span, false);
 
-  String get code() => '@@@';
+  String get code() {
+    world.internalError('Should not be getting code from raw EvaluatedValue',
+      span);
+  }
+
 
   EvaluatedValue get constValue() => this;
 
   // TODO(jimhug): Using computed code here without caching is major fear.
   int hashCode() => code.hashCode();
 
   bool operator ==(var other) {
     return other is EvaluatedValue && other.type == this.type &&
       other.code == this.code;
   }
@@ skipping 335 matching lines @@
 
 class ListValue extends EvaluatedValue {
   List<Value> values;
 
   ListValue(this.values, bool isConst, Type type, SourceSpan span):
     super(isConst, type, span);
 
   String get code() {
     final buf = new StringBuffer();
     buf.add('[');
-    for (var i=0; i < values.length; i++) {
+    for (var i = 0; i < values.length; i++) {
       if (i > 0) buf.add(', ');
       buf.add(values[i].code);
     }
     buf.add(']');
     var listCode = buf.toString();
 
     if (!isConst) return listCode;
 
     var v = new Value(world.listType, listCode, span);
     final immutableListCtor = world.immutableListType.getConstructor('from');
@@ skipping 270 matching lines @@
     }
 
     _ensureCode();
     return null;
   }
 }
 
 String _escapeForComment(String text) {
   return text.replaceAll('/*', '/ *').replaceAll('*/', '* /');
 }