textworld_data/dnd/logic/object.twl

# object
type o : t {
    predicates {
        combines_with(o, o, o);
        fresh(o);
        stored_item(o);
    }

    rules {
        combine :: $at(P, r) & in(o, I) & in(o', I) & combines_with(o, o', o'') & fresh(o'') -> in(o'', I);
    }

    reverse_rules {
        combine :: combine;
    }

    constraints {
        obj1 :: in(o, I) & in(o, c) -> fail();
        obj2 :: in(o, I) & on(o, s) -> fail();
        obj3 :: in(o, I) & at(o, r) -> fail();
        obj4 :: in(o, c) & on(o, s) -> fail();
        obj5 :: in(o, c) & at(o, r) -> fail();
        obj6 :: on(o, s) & at(o, r) -> fail();
        obj7 :: at(o, r) & at(o, r') -> fail();
        obj8 :: in(o, c) & in(o, c') -> fail();
        obj9 :: on(o, s) & on(o, s') -> fail();
    }

    inform7 {
        type {
            kind :: "object-like";
            definition :: "object-like is portable.";
        }

        predicates {
            combines_with(o, o', o'') :: "";
            fresh(o) :: "";
            stored_item(o) :: "";
        }

        commands {
            combine :: "combine {o} with {o'}" :: "unlocking the {o'} with the {o}";
        }

        code :: """
            Understand "combine [something] with [something]" as unlocking it with.
        """;
    }
}