sicp 2.53

Exercise 2.53.  What would the interpreter print in response to evaluating each of the following expressions?

 

 

(list 'a 'b 'c)

(list (list 'george))
(cdr '((x1 x2) (y1 y2)))

(cadr '((x1 x2) (y1 y2)))
(pair? (car '(a short list)))
(memq 'red '((red shoes) (blue socks)))

(memq 'red '(red shoes blue socks))

 

 

(define (memq item x)
  (cond ((null? x) #f)
        ((eq? item (car x)) #t)
        (else (memq item (cdr x)))))

(list 'a 'b 'c)
(list (list 'george))
(cdr '((x1 x2) (y1 y2)))
(cadr '((x1 x2) (y1 y2)))
(pair? (car '(a short list)))
(memq 'red '((red shoes) (blue socks)))
(memq 'red '(red shoes blue socks))

 

运行结果：

> (a b c)

> ((george))

> ((y1 y2))

> (y1 y2)

> #f

> #f

> #t