enodyt-4clojure-solution94.clj

;; enodyt's solution to Game of Life
;; https://4clojure.com/problem/94

(fn [board]
    (let [dx (count (first board))
          dy (count board)
          neighbours (fn [pos board]
                       (let [xs [[-1 -1] [0 -1] [1 -1]
                                 [-1  0]        [1  0]
                                 [-1  1] [0  1] [1  1]]]
                         (count (filter #(= % \#) 
                                        (map #(get-in board 
                                                      (map + pos %)) xs)))))]
    (map 
      #(apply str %) 
      (partition 
        dx 
        (for [x (range dx) y (range dy)] 
          (let [n (neighbours [x y] board)
                live? (= \# (get-in board [x y]))]
            (cond 
              (and live? (< n 2)) \space
              (and live? (or (= n 2) (= n 3))) \#
              (and live? (> n 3)) \space
              (and (not live?) (= n 3)) \#
              :else \space)))))))