+(defun intersection-p (list1 list2 &key (test #'eq))
+ (dolist (obj list1 nil)
+ (when (member obj list2 :test test)
+ (return-from intersection-p t))))
+
+
+(defun split-string (string delimiter)
+ (declare (simple-string string) (character delimiter))
+ (check-type string string)
+ (check-type delimiter character)
+ (let ((pos (position delimiter string)))
+ (if (not pos)
+ (list string)
+ (cons
+ (subseq string 0 pos)
+ (split-string (subseq string (1+ pos)) delimiter)))))
+
+(defun split-string-if (string predicate)
+ (declare (simple-string string))
+ (check-type string string)
+ (check-type predicate (or symbol function))
+ (let ((pos (position-if predicate string :start 1)))
+ (if (not pos)
+ (list string)
+ (cons
+ (subseq string 0 pos)
+ (split-string-if (subseq string pos) predicate)))))
+
+(defun concatenate-strings (strings &optional delimiter)
+ (if (not (rest strings))
+ (first strings)
+ (concatenate
+ 'string
+ (first strings)
+ (if delimiter (string delimiter) "")
+ (concatenate-strings (rest strings) delimiter))))
+
+(defun string-prefix-p (prefix string)
+ (and
+ (>= (length string) (length prefix))
+ (string= prefix string :end2 (length prefix))))