removing last element of a list(scheme)

Question

So I have to remove the last element of a list in scheme.

For example, let\'s say I have a list (1 2 3 4). I need to return:

(1 2 3)
         


        

Answer 1

I would write a simple recursion, altering the typical "empty? mylist" base case to "empty? (rest mylist)," so that I can return empty when the input list is only 1 element.

(define (removelast mylist)
  (cond
    [(empty? (rest mylist)) empty]
    [(cons? mylist) (cons (first mylist) (removelast (rest mylist)))]))

(removelast (list 1 2 3 4 5))

By the way, this code is in Racket/PLT Scheme, a subset of Scheme.