[rules-users] finding matching entries in parallel arrays

My problem boils down to finding matching entries in parallel arrays. Here is a rule that succesfully does just that: rule "Find matching entry in parallel arrays" when $first : ArrayList( ) $second : ArrayList( this != $first ) $i : Integer( this < $first.size ) eval( $first.get($i) == $second.get($i) ) then System.out.println ( "Found match at index " + $i + "!" ); end To execute this rule, I must insert (assert) the two ArrayList facts as well as at least as many Integer facts as there are items in the ArrayLists. What I don't like about this rule is that (1) I have to assert the Integers (2) I can't support arbitrarily-sized lists in my rules (without asserting that many Integer facts) So -- Is there a better way? What if a future version of Drools supported implicit Number facts that allowed for these kinds of indexing rules? Aaron