(cons (car x) (remove-if f (cdr x)))を評価する
(cons 0 (remove-if odd? '(1 2 3 4 5)) )
(define (remove-if f x)
(cond ((null? x)nil)
((f (car x)) (remove-if f (cdr x)))
(else (cons (car x) (remove-if f (cdr x)))) ))
新しいremove-ifを駆動