...or you can use predicate... I read somewhere that it's better than using eval. stub:PaymentStub($j : daysJuror, $p : daysPanel -> ($j + $p > 0)) -- View this message in context: http://drools-java-rules-engine.46999.n3.nabble.com/Adding-two-numbers-tp1205623p1209276.html Sent from the Drools - User mailing list archive at Nabble.com.