anchor.diff:  
   (defun %struct-name (obj)
     (if (not (arrayp obj))
  -    (%error "object is not a struct")
  -    (elt 0 obj)))
  +      (%error "object is not a struct")
  +      (elt 0 obj)))
   
   (defun %struct-fields (name)
     (with-queue form
  
positive.code:       (enqueue form (%struct-single-get name (%struct-field-name (car i)) index)))))
  
  (defun %struct-p (name)
    (let ((sym (%struct-p-symbol name)))
      `(defun ,sym (arr)
          (and (arrayp arr) (eq (elt arr 0) ,name)))))
  
  (defun %struct-sort-fields (fields-and-options)
    "Split list into fields and options."
  
negative.code: 
  (defun %struct-field-name (field)
    (if (consp field)
        (car field)
        field))
  
  (defun %struct-single-get (name field index)
    (with (sym (%struct-getter-symbol name field))
      `(progn
        (defun ,sym (arr)
          (elt arr ,index))
  