( map square '(3) )
(cons (square 3) (map square '( )) )
(cons 9 '( ) )
'( 9 )
(define (map f x)
(cond ((null? x) nil)
(else (cons (f (car x)) (map f (cdr x)))) ))
( map square '(3) )の評価は '( 9 )