# [racket] Looking for feedback on code style

On 9/9/10 11:26 AM, Eli Barzilay wrote:
>* On Sep 9, David Van Horn wrote:
*>>*
*>>* [...] As for the structure of the code as given, I would use helper
*>>* functions in place of the `let'. The resulting code will be easier
*>>* to read and the helper functions can be tested independently, making
*>>* it easier to maintain and improve the likelihood that the whole
*>>* program is correct; and correctness and ease of maintenance are
*>>* important aspects of style.
*>*
*>* Sounds like an overkill in this case, and for most values of
*>* "idiomatic" I'd say that it'd make it less so.
*
This is what I had in mind. I find this solution easier to read and
reason about. Is it really overkill? Less idiomatic?
#lang racket
(require test-engine/racket-tests)
;; A sample is represented as a non-empty list of real numbers.
;; Sample = [Pair Real [Listof Real]]
(check-expect (median (list 1)) 1)
(check-expect (median (list 1 2)) 3/2)
(check-expect (median (list 1 2 3)) 2)
(check-expect (median (list 3 1 2)) 2)
(check-expect (median (list 3 3 2)) 3)
;; Sample -> Real
(define (median lon)
(median-sorted (sort lon <)
(length lon)))
;; Sample Natural -> Real
;; lon is sorted, (= n (length lon)).
(define (median-sorted lon n)
(cond [(odd? n) (list-ref lon (quotient n 2))]
[else
(mean (list-ref lon (sub1 (quotient n 2)))
(list-ref lon (quotient n 2)))]))
;; Real Real -> Real
(define (mean r1 r2)
(/ (+ r1 r2) 2))
(test)