sicp-ex-4.49

meteorgan

  
  
 (define (list-amb li) 
   (if (null? li) 
       (amb) 
       (amb (car li) (list-amb (cdr li))))) 
  
 (define (parse-word word-list) 
   (require (not (null? *unparsed*))) 
   (require (memq (car *unparsed*) (cdr word-list))) 
   (let ((found-word (car *unparsed*))) 
     (set! *unparsed* (cdr *unparsed*)) 
     (list-amb (cdr word-list))))   ;; change 
  
 gets: 
 the student for the student studies for the student 
 the student for the student studie for the professor 
 the student for the student studie for the cat 
 the student for the student studie for the class 
 the student for the student studie for a student 
 the student for the student studie for a professor 
 the student for the student studie for a cat 
 the student for the student studie for a class 
 the student for the student studie to the student 
 the student for the student studie to the professor

donald

  
  
  
 (define (parse-word2 word-list) 
   (require (not (null? *unparsed*))) 
   (set! *unparsed* (cdr *unparsed*)) 
   (list (car word-list) (amb (cdr word-list))))