SICP 习题2.20 same-parity

(define same-parity
(lambda (x . y)
(define iter
(lambda (z res)
(if (null? z)
res
(if (= (remainder (car z) 2) (remainder x 2))
(iter (cdr z) (cons res (car z)))
(iter (cdr z) res)))))
(iter y x)))

(same-parity 1 2 3 4 5 6 7)