4. (letrec ((move (lambda (a b) (list ‘move a ’to b)))
(hanoi (lambda (a b c n)
(if (= 0 n) ()
(if (= n 1) (list (move a c))
(append (hanoi a c b (- n 1))
(cons (move a c) (hanoi b a c (- n 1)))))))))
(hanoi ‘a ’b ‘c 2))
((move a to b) (move a to c) (move b to c))
括弧ってすてきだよね? ネスト天国