9. my-map Write a function named my-map that works like the map function provide

Question

9. my-map
Write a function named my-map that works like the map function provided by the Scheme library and
demonstrated below. For example,
> (my-map (lambda (x) (+ x 1)) ’(1 2 3 4 5))
(list 2 3 4 5 6)

Here’s a definition of map
(define (map proc items)
(if (null? items)
nil
(cons (proc (car items))
(map proc (cdr items)))))
Using above definition:
> (map abs (list -10 2.5 -11.6 17))
(10 2.5 11.6 17)
> (map (lambda (x) (* x x)) (list 1 2 3 4))
(1 4 9 16)

12.

Define a procedure named zip that takes two lists and returns a list of pairs of the elements in the argument

> (zip (

((a 1) (b 2) (c 3))

3

lists. If the argument lists are of unequal lengths, the returned list should be truncated to the length of the

shorter list.

Explanation / Answer

#9 This question was a little strange since it seems like they basically give you the answer, but this does do what it's supposed to.

(define (my-map proc items)
(if (null? items)
'()
(cons (proc (car items))
(my-map proc (cdr items)))))

#12

(define (zip l1 l2)
(if (null? l1) '()
    (if (null? l2) '()
       (cons (list (car l1) (car l2)) (zip (cdr l1) (cdr l2))))))

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