+(defun join-trailing (list separator)
+ (if (null list)
+ ""
+ (concat (car list) separator (join-trailing (cdr list) separator))))
+
+(defun integer-to-string (x)
+ (if (zerop x)
+ "0"
+ (let ((digits nil))
+ (while (not (= x 0))
+ (push (mod x 10) digits)
+ (setq x (truncate x 10)))
+ (join (mapcar (lambda (d) (string (char "0123456789" d)))
+ digits)
+ ""))))
+