sicp-ex-4.68

meteorgan
  
  
 rule: 
 (assert! (rule (reverse () ()))) 
 (assert! (rule (reverse ?x ?y) 
                (and (append-to-form (?first) ?rest ?x) 
                     (append-to-form ?rev-rest (?first) ?y) 
                     (reverse ?rest ?rev-rest)))) 
  
 (reverse (1 2 3) ?x)  : infinite loop 
 ;;; Query input: 
 (reverse ?x (1 2 3)) 
  
 ;;; Query output: 
 (reverse (3 2 1) (1 2 3))