[racket] Calculating cumulative sum of the list

#lang racket

;; [Listof Number] -> [Listof Number]
;; given (a b c ...) produce (a (+ a b) (+ a b c) ...)
(define (cumulative-sum l #;"final private:" [so-far 0])
  (cond
    [(empty? l) '()]
    [else (define next (+ so-far (first l)))  
          (cons next (cumulative-sum (rest l) next))]))

(module+ main
  (cumulative-sum '(1 2 3)))

;; The comments are HtDP-style, but the optional entry parameter is not available in the teaching languages. 


On Jan 22, 2015, at 8:53 AM, Alexandr M <rus314 at gmail.com> wrote:

> Hello,
> 
> I am trying to replicate functionality of this code in Python:
> 
> https://gist.github.com/m-blog/22b7c5d31b3839ffba50#file-cumsum-py
> 
> in Racket without usage of any libraries.
> 
> What would the most optimal / concise way to do it in Racket?
> 
> Thank you.
> 
> -- 
> Best regards,
> Alex
> ____________________
>  Racket Users list:
>  http://lists.racket-lang.org/users