526 にも書いてるけど、変数の破壊的代入と再帰と末尾呼び出しの最適化はそれぞれ別々のものだと思うけどね

(let ((i 10)
(closures nil))
(labels ((iter ()
(if (zerop i)
nil
(progn
(push (lambda () i) closures)
(decf i)
(iter)))))
(iter)
(mapcar #'funcall closures)))
⇒ (0 0 0 0 0 0 0 0 0 0)



(let ((i 10)
(closures nil))
(dotimes (i i)
(let ((i i))
(push (lambda () i) closures)))
(mapcar #'funcall closures))
⇒ (9 8 7 6 5 4 3 2 1 0)