life.clj

;; cell
[1 2]

;; world
#{ [1 0] [1 1] [1 2]}

;; compute neighbors of a cell
(defn neighbors [[x y]]
  (for [dx [-1 0 1]
    dy (if (zero? dx)
    [-1 1]
    [-1 0 1])]
    [(+ x dx) (+ y dy)] ) )

(neighbors [1 1])

(def blinker #{[1 0] [1 1] [1 2]})

(map neighbors blinker)
(mapcat neighbors blinker)
(frequencies (mapcat neighbors blinker))
(defn live [n alive?]
  (or (= n 3)
      (and (= n 2) alive?)) )

(live 2 false)
(live 3 false)
(live 2 true)

;; putting it all together

(class blinker)
;; the blinker cell stuff
(#{[1 0]} [1 0])

(defn step [world]
  (set
  (for [[cell n] (frequencies(mapcat neighbors world))
        :when (live n (world cell))]
    cell)) )

(step (step blinker)) 

(defn life [initial-world]
  (iterate step initial-world))

(take 5 (life blinker))

(def glider #{ [0 1] [1 2] [2 0] [2 1] [2 2]})

(take 5 (life glider))