(quote a) -> a
(quote {}) -> {}

CL-USER> (quote ())
NIL

(defun as-keyword (sym)
  (intern (string sym) :keyword))

(defun slot->defclass-slot (spec)
  (let ((name (first spec)))
    `(,name :initarg ,(as-keyword name) :accessor ,name)))

(defmacro define-binary-class (name slots)
  `(defclass ,name ()
     ,(mapcar #'slot->defclass-slot slots)))

(define-binary-class id3-tag
    ((major-version)))

(DEFCLASS ID3-TAG NIL
      ((MAJOR-VERSION :INITARG :MAJOR-VERSION :ACCESSOR MAJOR-VERSION)))