Changeset 4482 for trunk/library/numberlist.lgt

Timestamp:

10/04/08 12:30:36 (3 months ago)

Author:

pmoura

Message:

Modified the implementation of the predicate product/2 in the library object "numberlist" to fail for empty lists.

Files:

• trunk/library/numberlist.lgt (modified) (3 diffs)

trunk/library/numberlist.lgt

@@ -5 +5 @@
 
     :- info([
-        version is 1.2,
+        version is 1.3,
         author is 'Paulo Moura',
-        date is 2008/4/22,
+        date is 2008/9/15,
         comment is 'List of numbers predicates.']).
 
@@ -21 +21 @@
         average(Ns, Lacc2, Sacc2, Average).
 
-    min([N| Ns], Min) :-
-        min(Ns, N, Min).
+    min([X| Xs], Min) :-
+        min(Xs, X, Min).
 
     min([], Min, Min).
-    min([N| Ns], Aux, Min) :-
-        (   N < Aux ->
-            min(Ns, N, Min)
-        ;   min(Ns, Aux, Min)
+    min([X| Xs], Aux, Min) :-
+        (   X < Aux ->
+            min(Xs, X, Min)
+        ;   min(Xs, Aux, Min)
         ).
 
-    max([N| Ns], Max) :-
-        max(Ns, N, Max).
+    max([X| Xs], Max) :-
+        max(Xs, X, Max).
 
     max([], Max, Max).
-    max([N| Ns], Aux, Max) :-
-        (   N > Aux ->
-            max(Ns, N, Max)
-        ;   max(Ns, Aux, Max)
+    max([X| Xs], Aux, Max) :-
+        (   X > Aux ->
+            max(Xs, X, Max)
+        ;   max(Xs, Aux, Max)
         ).
 
-    product(List, Product) :-
-        product(List, 1, Product).
+    product([X| Xs], Product) :-
+        product(Xs, X, Product).
 
     product([], Product, Product).
-    product([N| Ns], Acc, Product) :-
-        Acc2 is Acc * N,
-        product(Ns, Acc2, Product).
+    product([X| Xs], Acc, Product) :-
+        Acc2 is Acc * X,
+        product(Xs, Acc2, Product).
 
     sum(List, Sum) :-
@@ -53 +53 @@
 
     sum([], Sum, Sum).
-    sum([N| Ns], Acc, Sum) :-
-        Acc2 is Acc + N,
-        sum(Ns, Acc2, Sum).
+    sum([X| Xs], Acc, Sum) :-
+        Acc2 is Acc + X,
+        sum(Xs, Acc2, Sum).
 
     valid(-) :-     % catch variables and lists with unbound tails