readtable problem

(let ((char-table
  "|000 nul|001 soh|002 stx|003 etx|004 eot|005 enq|006 ack|007 bel
    |008 bs |009 ht |010 nl |011 vt |012 np |013 cr |014 so |015 si
    |016 dle|017 dc1|018 dc2|019 dc3|020 dc4|021 nak|022 syn|023 etb
    |024 can|025 em |026 sub|027 esc|028 fs |029 gs |030 rs |031 us
    |032 sp |127 del")
  (char-alias
  "|009 tab")
) (labels (
  (read-string (str &optional deb) (do ((pos 0) (x t) (l (length str)) (res))
    ((or (>= pos l)  (null x)) res)
    (setf l (length str))
    (setf (values x pos) (read-from-string str nil nil :start pos))
    (when deb (format t "read-string x=~s pos=~d~%" x pos))
    (push x res)
  ))
 (charkeys () (let ((res) (save-mac (get-macro-character #\|)))
  (set-macro-character #\| (lambda (stream char)
    (declare (ignore char)) (let ((code (read stream)) (sym (read stream))
      ) (format t "code ~a sym ~a~%" code sym)
        (list (values (intern (symbol-name sym) :keyword)) (code-char code)))
      ))
  (setf res (append (read-string char-table) (read-string char-alias)))
  (set-macro-character #\| save-mac)
  (reverse res)
  ))
) (let ((keys (charkeys)))
(defmacro charkey (x) (append `(case ,x) keys '((t nil)))
))
))
(defun tostring (x) "prepares an element for string concatenation"
  (apply #'concatenate 'string (typecase x
    (null (list ""))
    (character (list (list x)))
    (string (list x))
    (keyword (let ((y (charkey x))) (if y (list (list y)) (list (symbol-name x)))))
    (sequence (typecase (elt x 0)
      (function  (list (funcall #'tostring (apply (car x) (cdr x)))))
      (keyword (case (elt x 0)
        (:dec )
        (:oct )
        (:hex )
        (t (map 'list #'tostring x))
        ))
      (t (map 'list #'tostring x))
    ))
    (t (list (write-to-string x)))
  ))
)