#lang racket

(define (split _list)
    (define (spliter a b L _len)
        (if (null? L)
            (list a b)
            (if (<= _len (length a))
                (spliter a (append b (list (car L))) (cdr L) _len)
                (spliter (append a (list (car L))) b (cdr L) _len)
            )
        )
    )
    (spliter (list) (list) _list (/ (length _list) 2))
)
(define (merge _list1 _list2)
    (define (merger result L1 L2)
        (cond
            ((null? L1) (append result L2))
            ((null? L2) (append result L1))
            (else
                (if (< (car L1) (car L2))
                    (merger (append result (list (car L1))) (cdr L1) L2)
                    (merger (append result (list (car L2))) L1 (cdr L2))
                )
            )
        )
    )
    (merger (list) _list1 _list2)
)
(define (mergesort _list)
    (if (= 1 (length _list))
        _list
        (merge (mergesort (car (split _list)))
               (mergesort (car (cdr (split _list))))
        )
    )
)
(mergesort (list 9 5 6 2 41 2 4))