Now that we can see the up-to-date stock price for a given company, it makes sense to display a rolling average of the past, say, five stock prices. In a real scenario, this would provide an objective view of a company's share trend in the stock market.

Let's extend our program to accommodate this new requirement.

First, we'll need to modify our namespace definition:

(ns stock-market-monitor.core
  (:require [seesaw.core :refer :all])
  (:import (java.util.concurrent ScheduledThreadPoolExecutor
                                 TimeUnit)
           (clojure.lang PersistentQueue)))

The only change is a new import clause, for Clojure's PersistentQueue class. We will be using that later.

We'll also need a new label to display the current running average:

(def running-avg-label (label "Running average: -"))
(config! main-frame :content
         (border-panel
          :north  price-label
          :center running-avg-label
          :border 5))

Next, we need a function to calculate...