We don't publicise the internal javadocs, just the public ones. But just checkout the code and look over it, I don't think the internal javadocs will help much. You lose type discrimination and type safety, but you can already do: Map( this['key'] == "xxx" ) What I think would be more interesting is to use Traits and map a Map to a type safe structure. It would take a some changes, as at the moment the Traits back onto a global triple store, but they could with some changes back onto the provided Map instance. Traits is a form of duck typing. //code below is illustrative of what is possible, if changes where mad for above idea. // Create interface Person @Trait String : name int : age end // Identify the Map instance, and wrap it with the Person interface. rule $m : Map[ this['name'] != null, this['age'] != null ) then don( $m : Person.class ); end // Now the map is identified in a type safe manner. rule Person( name == "darth", age == 150 ) then …. end On 19 Aug 2012, at 13:56, Frank Wilson <fajwilson(a)gmail.com&gt; wrote: