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I'm a Clojure beginner and I implmeneted Game of life to learn how I should code things in Clojure.

(def state (ref [
 [false false false false false]
 [false false true false false]
 [false false true false false]
 [false false true false false]
 [false false false false false]]))
(defn get-state [state x y]
 (nth (nth state y) x))
(defn count-true-neighbours [state x y]
 (let [size (count state)]
 (->>
 (for [p (range (- x 1) (+ x 2))
 q (range (- y 1) (+ y 2))
 :when (not (and (= x p) (= y q)))]
 [p q])
 (map (fn [coord]
 (let [[p q] coord]
 (if (or (< p 0) (>= p size) (< q 0) (>= q size))
 false
 (get-state state p q)))))
 (filter true?)
 (count))))
(defn next-state-of [state x y]
 (let [alive (get-state state x y)
 alive-neighbours (count-true-neighbours state x y)]
 (cond
 (and (not alive) (= alive-neighbours 3)) true
 (and alive (or (= alive-neighbours 2) (= alive-neighbours 3))) true
 :else false)))
(defn next-state [state]
 (let [size (count state)]
 (mapv
 (fn [row]
 (mapv
 #(next-state-of state %1 row)
 (range 0 size)))
 (range 0 size))))
(defn pretty-print [state]
 (let [size (count state)]
 (loop [i 0]
 (if (< i size)
 (do
 (println
 (->>
 (nth state i)
 (mapv #(if %1 "■しかく " "□しろいしかく "))
 (reduce str)))
 (recur (inc i)))))))
(defn tick
 ([times] (tick 0 times))
 ([i times]
 (if (< i times)
 (do
 (dosync
 (println (str i ":"))
 (pretty-print @state)
 (ref-set state (next-state @state)))
 (recur (inc i) times))
 nil)))
(defn -main [& args]
 (tick 5))

I used ref to learn how to mange state. Using ref seems to be overkill for this tiny program.

As you see my code is terrible, but I couldn't improve this by myself.

I already checked this answer, but I think I did this in a quite different way and need different advises.

Thank you. (and I'm sorry I'm not a good English speaker if you have any inconveniences)