How to accumulate slots of facts?

Question

I have the following two deftemplates:

(deftemplate effect (slot type) (slot value) (slot explanation))
(deftemplate result (slot type) (slot total_value) (multislot total_explanation))

and the following deffacts:

(effect (type A) (value 1) (explanation "A is 1"))
(effect (type A) (value 2) (explanation "A is 2"))
(effect (type B) (value 3) (explanation "B is 3"))
(effect (type B) (value 4) (explanation "B is 4"))

I want to sum up the total values for facts of the same type resulting in:

(result (type A) (total_value 3) (total_explanation "A is 1" "A is 2"))
(result (type B) (total_value 7) (total_explanation "B is 3" "B is 4"))

How would I accumulate the slots of facts? Here's what I tried:

(defrule accumulate_typeA
(exists (effect (type A)))
=>
(bind ?sum 0)
(do-for-all-facts ((?f effect) (bind ?sum (+ ?sum ?f:value))
(bind ?expl (create$))
(do-for-all-facts ((?f effect) (bind ?expl (inserts ?f:explanation)))) 
(assert (result (type A) (total_value ?sum) (total_explanation ?expl))

Answer 1

         CLIPS (6.4 2/9/21)
CLIPS> 
(deftemplate effect 
   (slot type) 
   (slot value) 
   (slot explanation))
CLIPS>    
(deftemplate result 
   (slot type) 
   (slot total_value) 
   (multislot total_explanation))
CLIPS> 
(deffacts initial
   (effect (type A) (value 1) (explanation "A is 1"))
   (effect (type A) (value 2) (explanation "A is 2"))
   (effect (type B) (value 3) (explanation "B is 3"))
   (effect (type B) (value 4) (explanation "B is 4")))
CLIPS>    
(defrule accumulate_all_types
   =>
   (bind ?types (create$))
   (do-for-all-facts ((?f effect)) TRUE
      (if (not (member$ ?f:type ?types))
         then
         (bind ?types ?types ?f:type)))
   (foreach ?t ?types
      (bind ?sum 0)
      (bind ?expl (create$))
      (do-for-all-facts ((?f effect)) (eq ?f:type ?t)
         (bind ?sum (+ ?sum ?f:value))
         (bind ?expl ?expl ?f:explanation))
      (assert (result (type ?t) 
                      (total_value ?sum) 
                      (total_explanation ?expl)))))
CLIPS> (reset)
CLIPS> (run)
CLIPS> (facts)
f-1     (effect (type A) (value 1) (explanation "A is 1"))
f-2     (effect (type A) (value 2) (explanation "A is 2"))
f-3     (effect (type B) (value 3) (explanation "B is 3"))
f-4     (effect (type B) (value 4) (explanation "B is 4"))
f-5     (result (type A) (total_value 3) (total_explanation "A is 1" "A is 2"))
f-6     (result (type B) (total_value 7) (total_explanation "B is 3" "B is 4"))
For a total of 6 facts.
CLIPS>