How to define a slot of another template type in jess

Question

I have a template called Person, and this template has eyes, hands, body, and alot of other slots. But each one of these slots are other templates.
So how can I define a slot for template of other template type??
And how to define the facts ??

Here is an example of what I main:

(deftemplate Eyes
(slot colorOfEye (type STRING))
(slot ShapeOfEye (type STRING)))
(deftemplate Person 
(slot eye (type Eyes))
)
(deffacts People
(Person (eye ....))
)
(reset)

defining Person template is not working like this, and I don't know how to define the facts

Thanks

Answer 1

You have to define them both as separate templates. Then you can store either fact-id or some other identifier for the "sub-fact" in the main fact, then join the main fact pattern with a "sub-fact" pattern using that value:

(defrule blue-eyed-person
    (person (name ?name) (eyes ?eyes))
    ?eyes <- (eyes (color blue))
    =>
    (printout t ?name " has blue eyes." crlf))

Or alternatively

(defrule blue-eyed-person
    (person (name ?name) (eyes ?eyes))
    (eyes (id ?eyes) (color blue))
    =>
    (printout t ?name " has blue eyes." crlf))

To create the facts in the first place, you might say

(bind ?eyes (assert (eyes (color blue))))
(assert (person (name Fred) (eyes ?eyes)))