Question

Is it possible to do so? Let’s say I want to get the last element of a list, I would create a variable i = 0, and increment it until it equals to length. Any idea? An example would be greatly appreciated.

Thanks,

Answer 1

There are several ways to declare a variable; the cleanest one is let:

(let ((x some-expr))
  ; code block that uses x

But you don’t need this to get the last element of a list. Just use recursion:

(define (last xs)
  (if (null? (cdr xs))
    (car xs)
    (last (cdr xs))))

Note: if you want, you can use a variable to cache cdr‘s result:

(define (last xs)
  (let ((tail (cdr xs)))
    (if (null? tail)
      (car xs)
      (last tail))))