anchor.diff:  ;;;; * Walkers
   
   (deflisp1-walker form ()
  +  ;; By default all forms will stay the same.
     form)
   
   (deflisp1-walker if-form (consequent then else)
  +  ;; Transform the test and branches recursively.
     (new 'if-form
          :consequent (lisp1 consequent)
          :then       (lisp1 then)
          :else       (lisp1 else)))
   
   (deflisp1-walker lambda-function-form (arguments body)
  +  ;; For any function-form (ie lambda), we just transform the body.
  +  ;; We also must add the parameters to the list of bound variables.
     (let1 *bound-vars*
         (append (mapcar #'name arguments) *bound-vars*)
       (new 'lambda-function-form
  
positive.code: 
  (deflisp1-walker multiple-value-call-form (func arguments)
    (new 'multiple-value-call-form
         :func      (lisp1 func)
         :arguments (lisp1s arguments)))
  
  (deflisp1-walker multiple-value-prog1-form (first-form other-forms)
    (new 'multiple-value-prog1-form
         :first-form  (lisp1 first-form)
         :other-forms (lisp1s other-forms)))
  
  (deflisp1-walker symbol-macrolet-form (binds body)
  
negative.code: 	 :body      (lisp1s body))))
  
  (deflisp1-walker free-variable-reference (name)
    ;; If a free variable is bound in the toplevel, *and* not bound by
    ;; an enclosing lambda, then we'll return that function.  We take
    ;; advantage of the fact that the `name' slot is shared.
    (if (and (fboundp name) (not (member name *bound-vars*)))
        (change-class form 'free-function-object-form)
        form))
  
  (deflisp1-walker application-form (operator arguments)
    ;; We transform all applications so they use explicit funcall.  We
    ;; also must take into account ((a b) c ...) which must also
    ;; transform the operator accordingly.
    (new 'free-application-form
         :operator  'funcall
         :arguments (cons (if (not (typep operator 'form))
  