How to implement collections (e.g. list) in CLIPS and how to interrogate such a collection

[Pointer2VoidStar]

I am using fuzzyCLIPS 6.31 and I want to have a fact that is a collection (of other facts). Currently, I have something like this:

(deftemplate person "attributes of a person" 

      (multislot name (type STRING) ) (slot age (type FLOAT) (range 0.0 129.9) (default 0)

      (slot gender (type SYMBOL) (allowed-symbols male female) ) 

       ; .. other attributes 

) 

(def template people "collection of people" ; terminating char separated string of string representation of person 

 ; e.g. "John Frederick Handel, 42.5, male, ....;Homer Jay Simpson, 45.2, male, ..." 

 (slot members (type STRING) ) 

) 

 (defrule make-person-and-add-to-group ; make a person fact ; amend previously asserted people fact by adding "stringified" person to people fact

 ) 

 (defrule predict-a-riot 

  ; IF we have (fuzzy) "too" many males in a group AND 

 ; the males are above the age of 'X' AND 

 ; some other salient facts 

 ; => THEN ; assert riot prediction with CF

 )

This could be an example of a simplistic expert system that attempt to predict the likelihood of a riot breaking out, based on some simplistic input variables and heuristics.

I have the following questions:

1. Is "stringifying" facts (concatenating and then parsing/groking the resulting string) a good/acceptable way of dealing with lists (or collections) of facts ?
2. How does one access and manipulate the string held in a slot of a fact?

[CLIPS Support]

Create a unique id for each person fact and store that in your collection rather than the content of the fact.

         CLIPS (6.31 6/12/19)

CLIPS> 

(deftemplate person

   (slot id (type SYMBOL))

   (slot name (type STRING))

   (slot age (type INTEGER) (range 0 130) (default 0))

   (slot gender (type SYMBOL) (allowed-symbols male female)))

CLIPS> 

(deftemplate people 

   (multislot members (type SYMBOL)))

CLIPS>    

(deffacts initial

   (people)

   (add-person))

CLIPS> 

(deffunction add-person ()

   (printout t "Name: ")

   (bind ?name (readline))

   (printout t "Age: ")

   (bind ?age (read))

   (printout t "Gender: ")

   (bind ?gender (read))

   (bind ?id (gensym*))

   (assert (person (id ?id)

                   (name ?name)

                   (age ?age)

                   (gender ?gender)))

   (return ?id))

CLIPS>                    

(defrule make-person-and-add-to-group

   ?p <- (people (members $?people))

   ?a <- (add-person)

   =>

   (retract ?a)

   (printout t "Add Person? ")

   (bind ?response (lowcase (read)))

   (if (or (eq ?response y) (eq ?response yes))

      then

      (bind ?id (add-person))

      (modify ?p (members ?id ?people))

      (assert (add-person))))

CLIPS> (reset)

CLIPS> (run)

Add Person? yes

Name: Fred Smith

Age: 38

Gender: male

Add Person? yes

Name: Sally Jones

Age: 23

Gender: female

Add Person? no

CLIPS> (facts)

f-0     (initial-fact)

f-3     (person (id gen1) (name "Fred Smith") (age 38) (gender male))

f-6     (person (id gen2) (name "Sally Jones") (age 23) (gender female))

f-7     (people (members gen2 gen1))

For a total of 4 facts.

CLIPS> 

The general pattern then for doing something to each member of the collection is:

(defrule for-each-person

   (people (members $? ?id $?))

   (person (id ?id)

           (name ?name)

           (age ?age)

           (gender ?gender))

   =>

   ;; Action

   )