[rules-users] Getting the return from a funcion

Hi! I'm new here and a have a doubt about rules and functions in Drools. I have this rule: rule "ProductDescription validation" when $listing : Listing( $description:productDescription != null ) eval( $description.getTitle() != null ) eval( hasForbiddenWordsSet( wordsSet, $description.getTitle() ) ) then System.out.println("ERROR!"); end And this function: function boolean hasForbiddenWordsSet(Set wordsSet, String value) { #do something useful here } And everything works fine. But now I want that function "hasForbiddenWordsSet" return a String. For example to print at "then". I tried something like this: rule "ProductDescription validation" when $listing : Listing( $description:productDescription != null ) eval( $description.getTitle() != null ) $word : hasForbiddenWordsSet( wordsSet, $description.getTitle() ) then System.out.println("ERROR: " + word); end function String hasForbiddenWordsSet(Set wordsSet, String value) { #do something useful here } But it doesn't work, tried some other things and still no success. Could someone help me? Thanks in advance. -- Leandro Carvalho