anchor.diff:    (rplaca (cdr form) (lassoc var frames))
     (resolve-variables-aux-recurse form frames))
   
  -(define-resolve-variables-aux (let varrecs . body)
  +(define-resolve-variables-aux (let varrecs body)
     (resolve-variables-aux-recurse form (cons varrecs frames)))
   
  -(define-resolve-variables-aux (lambda attrs . body)
  +(define-resolve-variables-aux (lambda attrs body)
     (resolve-variables-aux-recurse form (cons (attr-ref attrs 'params) frames)))
   
   (define (resolve-variables form)
  
positive.code:             (list 'make-box () (quoted-unspecified))
              (quoted-unspecified))))
  
  (define-introduce-boxes (let varrecs . body)
    (introduce-boxes-recurse form)
    (dolist (varrec varrecs)
      (when (varrec-written? varrec)
        (rplacd (cdr form) (cons (initialize-var-form varrec) (cddr form))))))
  
  (define (init-boxed-param-form varrec temprec)
    (quasiquote (set! (unquote varrec) (make-box () (ref (unquote temprec))))))
  
  (define-introduce-boxes (lambda attrs . body)
    (introduce-boxes-recurse form)
    (let* ((let-form false))
      (nmapfor (varrec (attr-ref attrs 'params))
        (if (varrec-boxed? varrec)
            (let* ((temprec (list (gensym))))
              (unless let-form
                (set! let-form (cons () body))
                (rplacd (cdr form) (list (cons 'let let-form))))
              (rplaca let-form (cons varrec (car let-form)))
              (rplacd let-form (cons (init-boxed-param-form varrec temprec)
                                     (cdr let-form)))
              temprec)
            varrec))))
  
  ;;; Calculate indices for variables
  
  
negative.code:     (varrec-attr-set! varrec 'written
                        (= 2 (varrec-attr-remove varrec 'state)))))
  
  (define-classify-variables (let varrecs body)
    (classify-block-variables varrecs 1 form))
  
  (define-classify-variables (lambda attrs body)
    (classify-block-variables (attr-ref attrs 'params) 0 form))
   
  ;;; Now definition information is captured in the lets, replace
  