speed-control.rkt

#|
https://www.codewars.com/kata/56484848ba95170a8000004d/train/racket

I know I said I'm done with racket, but I have created mental debt by training myself on an industry-undesirable language :(.
|#

#lang racket
(provide gps)

(define (gps s x)
  (match x
    [(or (list) (list _)) 0]
    [_
      (for/fold ([acc empty]
                 #:result (argmax identity acc))
                ([a (in-list x)]
                 [b (in-list (cdr x))])
        (define value (inexact->exact (floor (abs (/ (* 3600 (- a b)) s)))))
;;        (printf "~a - ~a = ~a\n" a b value)
        (cons value acc))]))