Changeset 4216 for trunk/library/set.lgt

Timestamp:

04/22/08 08:09:59 (5 months ago)

Author:

pmoura

Message:

Updated the definitions of the predicate valid/1 for the library objects "list", "list(Type)", "numberlist", "set", "set(Type)", "varlist" to fail for lists with unbound tails after discussion with Jan Wielemaker and Ulrich Neumerkel.

Files:

• trunk/library/set.lgt (modified) (2 diffs)

trunk/library/set.lgt

@@ -5 +5 @@
 
     :- info([
-        version is 1.0,
+        version is 1.1,
         author is 'Paulo Moura',
-        date is 2000/7/24,
+        date is 2008/4/22,
         comment is 'Set predicates implemented using ordered lists. Uses ==/2 for element comparison and standard term ordering.']).
 
@@ -179 +179 @@
         union([Head1| Tail1], Tail2, Union).
 
-    valid(Set) :-
-        nonvar(Set),
-        valid2(Set).
+    valid(-) :-             % catch variables
+        !,
+        fail.
+    valid([]) :-
+        !.
+    valid([Element| Set]) :-
+        check_order(Set, Element).
 
-    valid2([]) :-
+    check_order(-, _) :-    % catch unbound tails
+        !,
+        fail.
+    check_order([], _) :-
         !.
-    valid2([_]) :-
-        !.
-    valid2([Element1, Element2| Set]) :-
-        Element1 @< Element2,
-        valid2([Element2| Set]).
+    check_order([Element2| Set], Element1) :-
+        Element2 @> Element1,
+        check_order(Set, Element2).
 
 :- end_object.