Fixed many bugs.

src/java/book/PersistentSortedList.java

@@ -13,11 +13,11 @@ public class PersistentSortedList extends Obj implements Iterable, RandomAccess,
                                                          List, Counted{
     final private PersistentTreeMap impl;
     final private int _count;
-    static public final PersistentSortedList EMPTY = new PersistentSortedList(null, PersistentTreeMap.EMPTY, 0);
+    static private final PersistentSortedList EMPTY_DEFAULT_COMPARATOR = new PersistentSortedList(null, PersistentTreeMap.EMPTY, 0);
     private int _hasheq = 0;
 
     public static PersistentSortedList create(ISeq items){
-        PersistentSortedList ret = EMPTY;
+        PersistentSortedList ret = EMPTY_DEFAULT_COMPARATOR;
         for(; items != null; items = items.next()){
             ret = ret.cons(items.first());
         }
@@ -52,7 +52,9 @@ public class PersistentSortedList extends Obj implements Iterable, RandomAccess,
 
     @Override
     public IPersistentCollection empty() {
-        return PersistentSortedList.EMPTY;
+        return new PersistentSortedList(null,
+                new PersistentTreeMap(null, this.impl.comp),
+                0);
     }
 
     @Override
@@ -142,7 +144,7 @@ public class PersistentSortedList extends Obj implements Iterable, RandomAccess,
     @Override
     public ISeq more() {
         ISeq s = next();
-        return s == null ? PersistentSortedList.EMPTY : s;
+        return s == null ? (PersistentSortedList) empty() : s;
     }
 
     @Override