Mob programming a simple rate limiter

rate_limiter.clj

(ns rate-limiter
  (:require [clojure.core.async :refer [go-loop] :as async]))

(def config {:num-mseconds 5000 :max-requests 10})

(def counter (atom 0))

(defn rate-limited? [counter]
  (>= @counter (:max-requests config)))

(defn request []
  (when-not (rate-limited? counter)
    (swap! counter inc)))

(def stop (async/chan))

(defn start []
  (go-loop []
    (let [c (async/timeout (:num-mseconds config))
          [_ chan] (async/alts! [c stop])]
      (println "***" (= chan c))
      (when (= chan c)
        (reset! counter 0)
        (recur)))))

(defn do-n-requests [count]
  (dotimes [n count]
    (println (request))))