Small Town

small_town.cljs

(ns small-town.app)

;; person

(def genders #{:male :female})

(defn make-person [age]
  {:age age
   :gender (rand-nth (vec genders))
   :dead false})

(defn age [{:keys [age] :as person}]
  (let [next-age (inc age)]
    (cond-> person
      (>= next-age 15)
      (assoc :dead true)

      true
      (assoc :age next-age))))

(def male? (comp boolean #{:male} :gender))
(def female? (complement male?))

;; town

(defn make-town [{:keys [people] :as town}]
  (assoc town :people (repeatedly people make-person)))

(defn render [{:keys [people food] :as town}]
  (let [elem (.. js/document (createElement "DIV"))]
    (aset elem "innerHTML"
          (str
           "<p>"
           "People: " (pr-str people)
           "<br/>"
           "Food: " (pr-str food)
           "</p>"))
    elem))

(defn population-eats [{:keys [eating-rate food people] :as town}]
  (update town :food (fn [f]
                       (- f (* (count (filter (comp not :dead) people)) eating-rate)))))

(defn population-ages [{:keys [people] :as town}]
  (update town :people (fn [peeps]
                         (map age peeps))))

(defn gravedigger-works [{:keys [people] :as town}]
  (update town :people (partial remove :dead)))

(defn turn [{:keys [food people eating-rate] :as town}]
  (-> town
      population-eats
      population-ages
      gravedigger-works))

(defn init []
  (let [c (.. js/document (createElement "DIV"))
        town (atom (make-town {:food 500000
                               :people 10
                               :eating-rate 12}))]

    (js/setInterval (fn []
                      (let [new-town (swap! town turn)]

                        (.. js/document (getElementById "container") (appendChild (render new-town)))))
                    1000)))