(defun quickselect (n _list)
  (let* ((ys (remove-if (lambda (x) (< (car _list) x)) (cdr _list)))
         (zs (remove-if-not (lambda (x) (< (car _list) x)) (cdr _list)))
         (l (length ys))
         )
    (cond ((< n l) (quickselect n ys))
          ((> n l) (quickselect (- n l 1) zs))
          (t (car _list)))
    )
  )

(defparameter a '(9 8 7 6 5 0 1 2 3 4))
(format t "~a~&" (mapcar (lambda (x) (quickselect x a)) (loop for i from 0 below (length a) collect i)))