Scheme - getting rid of extra parentheses

Author

getting rid of extra parentheses

kiat

2004-07-13, 11:17 pm

Hi,

Could someone help me with the task below? If you're concerned that I might be a student doing Scheme as a curriculum subject and I'm s

ing quick solutions here, rest assured that I'm not. I'm self-learning Scheme to improve my programming skills.

;;;;
Exercise 2.8.3

Define the procedure make-list, which takes a nonnegative integer n and an object and returns a new list, n long, each element of which is the object.

(make-list 7 '())
=> (() () () () () () ())
;;;;

This is as far as I've got:

code:
(define make-list
  (lambda (n obj)
    (cond 
      ((= n 1) 
        obj)
        (list (list obj (make-list (- n 1) obj))))))
(make-list 3 '())
=> (() (() ()))

Thanks in advance :)

kiat

2004-07-14, 5:14 am

I think I may have found the solution:

code:
(define make-list
  (lambda (n obj)
    (cond 
      ((= n 1) 
        (list obj))
        (list (cons obj (append (make-list (- n 1) obj)))))))
(make-list 7 '())

Sponsored Links