Mergesort in Racket in R5RS

I'm trying to write mergesort in Racket (in R5RS).

I'm not sure how I'm getting so many syntax errors.

So, I've learned from the help of those who commented that I was actually writing in R and not R5RS. I'm new to learning either language so I would appreciate any help with how to write a mergesort method in R5RS. I removed most of the causes of the syntax errors such as

Illegal use of '['

but then it didn't do anything.

This is the code I had before fixing the program

(define (merge as bs)
        (match* (as bs)
        [((list) bs) bs]
        [(as (list)) as]
        [((list a as ...) (list b bs ...))
(if (< a b)
        (cons a (merge as (cons b bs)))
        (cons b (merge (cons a as) bs)))]))
(define (mergesort vs)
        (match vs
        [(list) vs]
        [(list a) vs]
[_ (define-values (lvs rvs)
        (split-at vs (quotient (length vs) 2)))
        (merge (mergesort lvs) (mergesort rvs))]))

This is after I fixed it but it still didn't work

(define (merge as bs)
        (match* (as bs)
        ((list) bs) bs
        (as (list)) as
        ((list a as ...) (list b bs ...))
(if (< a b)
        (cons a (merge as (cons b bs)))
        (cons b (merge (cons a as) bs)))))

(define (mergesort vs)
        (match vs
        (list) vs
        (list a) vs
(define-values (lvs rvs)
        (split-at vs (quotient (length vs) 2)))
        (merge (mergesort lvs) (mergesort rvs))))

EDIT: I appreciate the help with understanding the mistake I made here. I have formatted the code better so it is indented.

Solution

If you're using Racket's R5RS language you need to write programs which are in that language: it won't work to write programs in some other language. In this case, match at least is not R5RS, and I strongly suspect split-at and define-values are not either.

What you're doing is a bit like pointing a FORTRAN 77 compiler at a Fortran 2018 program and expecting it to cope.

(Also: indent your code!)