anchor.diff:                   (cond
                      ((and (eq 's-prime (item-symbol item))
                            (= 1 (item-position item)))
  -                    (when (member 'eof la)
  -                      (set-action k (list 'eof)
  +                    (when (member 'yacc-eof-symbol la)
  +                      (set-action k (list 'yacc-eof-symbol)
                                     (make-accept-action)
                                     (item-production item))))
                      (t
  
positive.code: (defpackage #:yacc
    (:use #:common-lisp)
    (:export #:make-production #:make-grammar #:make-parser #:parse-with-lexer
             #:define-grammar #:define-parser
             #:yacc-parse-error #:yacc-parse-error-terminal
             #:yacc-parse-error-value #:yacc-parse-error-expected-terminals)
    #+CMU
  
negative.code:       (let ((stack (list 0)) symbol value)
          (flet ((next-symbol ()
                   (multiple-value-bind (s v) (funcall lexer)
                     (setq symbol (or s 'yacc-eof-symbol) value v))))
            (next-symbol)
            (loop
             (let* ((state (car stack))
  