How do I convert from list to vector this function? (scheme-dr racket)

Question

(define l1 (list 1 2 3))
(define l2 (list 4 5 6))

(define (concatenar l1 l2)
        (if (null? l1) l2
        (cons (car l1) (concatenar (cdr l1) l2)))
 )

My result be a list '(1 2 3 4 6 7 8 9)

but I want a vector to come out

I know what is done with this function: vector->list But I do not know how to implement it

Answer 1

Rename your existing procedure to concatenar-helper and write a wrapper procedure:

(define (concatenar-helper l1 l2)
  (if (null? l1)
      l2
      (cons (car l1) (concatenar-helper (cdr l1) l2))))

(define (concatenar l1 l2)
  (list->vector (concatenar-helper l1 l2)))