sicp-ex-4.11

  
  
  
  
 (define (make-frame variables values) 
         (if (= (length variables) (length values)) 
                 (map cons variables values) 
                 (error "length mimatch -- MAKE-FRAME" variables values))) 
  
 (define (frame-variables frame) (map car frame)) 
 (define (frame-values frame) (map cdr frame))