How do I handle a variable number of arguments passed to a function in Racket?

Question

I like creating functions which take an unlimited number of arguments, and being able to deal with them as a list. It\'s been useful to me when creating binary trees & I

Answer 1

There's nothing improper about the list received as a variadic argument list (meaning: variable number of arguments). For example:

(define test-list
  (lambda xs
    (length xs))) ; xs is a normal list, use it like any other list

(test-list 1 2 3 4)
=> 4

In the above example, the xs parameter is a normal, plain, vanilla list, there's nothing improper about it. You can iterate over it as you would over any other list. There's no need to car it, it's already a list! Also, notice that the same function can be written like this:

(define (test-list . xs)
  (length xs))   ; xs is a normal list, use it like any other list

Just for reference: an improper list is one that does not end with the null list. For example: '(1 2 3 . 4). Again, that's not how a variadic argument list looks.