anchor.diff:            ((:constant) +symbol-mode-constant+)
             ((:symbol-macro) +symbol-mode-symbol-macro+)))
     value)
  +
  +(setf (symbol-mode 'nil) :constant)
  +
  +(defun variable-information (symbol)
  +  (symbol-mode symbol))
   
   ;;; The compiler can only handle (apply function arg-list).
   (defun apply (function arg &rest more-args)
  
positive.code:   name)
  
  (defun macro-function (symbol &optional env)
    (when env
      (error "TODO: Macro-function in environment."))
    (get symbol '%macro-function))
  
  (defun (setf macro-function) (value symbol &optional env)
    (when env
  
negative.code:                                    (declare (ignore r))
                                     (error 'undefined-function :name symbol))
          (get symbol '%macro-function) value))
  
  (defun symbol-macro-function (symbol)
    nil)
  
  ;;; Calls to these functions are generated by the compiler to
  ;;; signal errors.
  