全域性特殊變數在各處都很特殊

因此這些變數將使用動態繫結。

(defparameter count 0)
;; All uses of count will refer to this one 

(defun handle-number (number)
  (incf count)
  (format t "~&~d~%" number))
  
(dotimes (count 4)
  ;; count is shadowed, but still special
  (handle-number count))
  
(format t "~&Calls: ~d~%" count)
==>
0
2
Calls: 0

為特殊變數提供不同的名稱以避免此問題：

(defparameter *count* 0)

(defun handle-number (number)
  (incf *count*)
  (format t "~&~d~%" number))
  
(dotimes (count 4)
  (handle-number count))
  
(format t "~&Calls: ~d~%" *count*)
==>
0
1
2
3
Calls: 4

注 1：在某個範圍內不可能使全域性變數非特殊。沒有宣告來製作變數詞法。

注 2：可以使用 special 宣告在本地上下文中宣告一個特殊變數。如果該變數沒有全域性特殊宣告，則宣告僅在本地並且可以被遮蔽。

(defun bar ()
  (declare (special a))
  a)                       ; value of A is looked up from the dynamic binding

(defun foo ()
  (let ((a 42))            ; <- this variable A is special and
                           ;    dynamically bound
    (declare (special a))
    (list (bar)
          (let ((a 0))     ; <- this variable A is lexical
            (bar)))))

> (foo)
(42 42)