Thanks for sharing this. Coincidentally, I just wrote my first Clojure
program which was... an implementation of Conway's Game of Life :-) I took a
different approach - I represented the board as a vector of vectors of
integers (1 for alive, 0 for dead) and then implemented a new-board function
that takes a board as an argument and returns the next generation of that
board. It seemed the functional way to do it. I then create an atom whose
state is a grid and repeatedly call (swap! board new-board) in order to move
it through the generations.
I'll copy the source to my little program at the bottom of this email. If
anyone has any comments on the style or possible improvements then I would
be very interested to hear them. I'm particularly keen to hear how close to
idiomatic Clojure style it is (is there a Clojure equivalent of the
adjective "Pythonic"?)
(import
'(java.awt Color Graphics Dimension FlowLayout)
'(javax.swing JPanel JFrame JButton Timer BoxLayout)
'(java.awt.event MouseListener ActionListener ActionEvent))
(set! *warn-on-reflection* true)
(def width 50)
(def height 20)
(def cell-width 10)
(def cell-height 10)
(def sleep-time 100)
(def initial-board
; (apply vector (replicate height
; (apply vector (replicate width 0)))))
[[0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0] [0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0] [0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0] [0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0] [0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0] [0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 1 0 0 0 0 1 1 0 0 0 0
0 0 0 0] [0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1
1 0 1 1 0 0 0 1 1 0 0 0 0 0 0 0 0] [0 0 0 0 0 0 1 1 0 0 1 1 0 0 0 0 0 0 1 0
0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0] [0 0 0 0 0 0 1
1 0 1 0 0 1 0 0 1 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0] [0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0
0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0] [0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0] [0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0] [0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0] [0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0] [0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0] [0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0] [0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0] [0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0] [0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0] [0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0]])
(def board-atom (atom initial-board ))
(def running-atom (atom false))
;; Board manipulation functions
(defn print-board [b]
(doseq [row b]
(println (str row))))
(defn within [v min max]
(and (>= v min) (< v max)))
(defn cell-at [b x y]
(if (and (within x 0 width) (within y 0 height))
(nth (nth b y) x)
0))
(defn occurences [l item]
(count (filter #(= % item) l)))
(defn new-cell-value [cell neighbours]
(let [num-1s (occurences neighbours 1)]
(if (= cell 0)
; cell is currently dead and will become alive iff it has 3 living
; neighbours
(if (= num-1s 3) 1 0)
; else cell is currently alive and will die iff it has fewer than 2 or
; more than 3 living neighbours
(if (or (< num-1s 2) (> num-1s 3)) 0 1))))
(defn cell-neighbours [b x y]
[(cell-at b (- x 1) (- y 1))
(cell-at b x (- y 1))
(cell-at b (+ x 1) (- y 1))
(cell-at b (- x 1) y)
(cell-at b (+ x 1) y)
(cell-at b (- x 1) (+ y 1))
(cell-at b x (+ y 1))
(cell-at b (+ x 1) (+ y 1))])
(defn new-value-at [b x y]
(let [cell (cell-at b x y)
neighbours (cell-neighbours b x y)]
(new-cell-value cell neighbours)))
(defn new-board [b]
(vec (for [y (range height)]
(vec (for [x (range width)]
(new-value-at b x y))))))
(defn flip-cell [b x y]
(let [row (nth b y)
cell (nth row x)
new-cell (- 1 cell)
new-row (assoc row x new-cell)]
(assoc b y new-row)))
(defn apply-n-times [f n x]
(if (zero? n)
x
(recur f (dec n) (f x))))
;; GUI functions
(defn make-action-listener [f]
(proxy [ActionListener] [] (actionPerformed [e] (f e))))
(defn render [#^Graphics g b]
(doseq [y (range height)]
(doseq [x (range width)]
(let [cell (cell-at b x y)]
(if (= cell 0)
(.setColor g Color/WHITE)
(.setColor g Color/BLACK))
(.fillRect g (* x cell-width) (* y cell-height)
(dec cell-width) (dec cell-height))))))
(defn make-board-panel []
(let [panel
(proxy [JPanel MouseListener] []
(paint [g] (render g @board-atom))
(getPreferredSize [] (Dimension. (* width cell-width)
(* height cell-height))))]
(doto panel
(.addMouseListener (proxy [MouseListener] []
(mouseClicked [e]
(let [x (int (/ (.getX e) cell-width))
y (int (/ (.getY e) cell-height))]
(swap! board-atom flip-cell x y)))
(mousePressed [e])
(mouseReleased [e])
(mouseEntered [e])
(mouseExited [e]))))))
(defn make-button [text action]
(doto (JButton. text)
(.addActionListener (make-action-listener action))))
(defn make-control-panel []
(let [control-panel (JPanel.)]
(doto control-panel
(.setLayout (BoxLayout. control-panel BoxLayout/Y_AXIS))
(.add (make-button "Start" (fn [e]
(swap! running-atom (constantly true)))))
(.add (make-button "Stop" (fn [e]
(swap! running-atom (constantly false)))))
(.add (make-button "Step" (fn [e]
(swap! board-atom new-board)))))))
(defn make-frame []
(let [frame (JFrame. "Life")]
(doto (.getContentPane frame)
(.setLayout (FlowLayout.))
(.add (make-board-panel))
(.add (make-control-panel)))
(add-watch board-atom "repaint" (fn [k r o n] (.repaint frame)))
(doto frame
(.pack)
(.show))
frame))
(defn go [b]
(let [frame (make-frame)]
(.start (Timer. sleep-time (make-action-listener
(fn [e] (when @running-atom
(swap! b new-board))))))))
(go board-atom)
2009/11/16 solussd <solu...@gmail.com>
> I just finished an implementation of the Conway's Game of Life
> derivative, Highlife, in Clojure. It consists of a simple swing GUI
> and makes good use of Refs for coordinating grid updates. A more
> detailed description, source, and jars can be found here:
> http://www.solussd.com/2009/11/a-clojure-highlife/ enjoy!
>
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