brians-brain.clj

(def board 
  (-> (vec (repeat 5 (vec (repeat 5 :off))))
    (assoc-in [0 0] :on)
    (assoc-in [0 1] :on)
    (assoc-in [1 2] :on)))

(defn neighbors-on [above [left _ right] below]
  (count (filter #{:on} (concat above [left right] below))))

(defn torus-windows [coll]
  (partition 3 1 (concat [(last coll)] coll [(first coll)])))

(defn rule [above current below]
  (let [self (second current)]
    (cond
      (= :on self) :dying
      (= :dying self) :off
      (= 2 (neighbors-on above current below)) :on
      :else :off)))

(defn step [board]
  (map (fn [window] 
         (apply #(apply map rule %&) (map torus-windows window))) 
    (torus-windows board)))

(defn show [board]
  (doseq [row board]
    (println (apply str (map {:on \X :off \space :dying \.} row)))))

; (time (nth (iterate step board) 100))

(doseq [board (take 10 (iterate step board))]
  (println "-----------")
  (show board))