(defun variable-p (x) (and (symbolp x) (char= (char (symbol-name x) 0) #\?)))文字列の要素をとり出すには,charの他にeltでも可能である.
> (symbol-name 'abc) "ABC" > (symbol-name '?abc) "?ABC" > (elt "abc" 0) #\a > (char "abc" 1) #\b > (variable-p '?a) T > (variable-p '??) T > (variable-p '*?) NIL > (variable-p 'abc) NIL