to answer your question directly, you would need to do something like
this to make it work the way your example is set up:
(defn new-game []
(let [board (atom (into [] (repeat 9 nil)))]
(fn [n & [i]]
(cond
(= n :x) (swap! board assoc i 'x)
(= n :o) (swap! board assoc i 'o)
(= n :print) (println @board)))))
(def g1 (new-game))
(g1 :x 0)
(g1 :print)
On Thu, Apr 19, 2012 at 9:58 PM, Armando Blancas <abm221...@gmail.com> wrote:
> You could keep the board in an atom so it can mutate; then try to find maybe
> two good places for mutation to happen, your move and the program's. With
> the rest being functional you'll avoid the problems of global state while
> not being forced to fit your logic into a loop of some re-binding that
> simulates mutation.
>
>
> On Thursday, April 19, 2012 3:21:56 PM UTC-7, Craig Ching wrote:
>>
>> Ok, I've read that what I want to do is a no no. But this is the sort of
>> thing I did in Scheme about 20 years ago (and because of that I'm probably
>> misremembering ;-)).
>>
>> Basically I'm learning clojure and thought I'd write a tic tac toe game.
>> But not any tic tac toe, I want to write one where I can have multiple
>> games going simultaneously. Something like:
>>
>> (def g1 (new-game))
>> (def g2 (new-game))
>>
>> (g1 :x 0)
>> (g1 :print)
>> (g2 :x 5)
>> (g2 :print)
>>
>> So the schemer in me (and probably the imperative programmer as well)
>> thought I could return a clojure that encapsulates the board value,
>> something like this:
>>
>> (defn new-game []
>>
>> (let [board (into [] (repeat 9 nil))]
>>
>> (fn [n i]
>>
>> (cond
>>
>> (= n :x)(set! board (assoc board i 'x))
>>
>> (= n :o)(set! board (assoc board i 'o))
>>
>> (= n :print) (println board)))))
>>
>>
>> Of course I get an error saying I can't bind to the non-mutable board.
>>
>> I'm really new to Clojure, so apologies if this is really basic for this
>> list. Can I do what I want or can someone point me in the right direction?
>> I've seen some other tic tac toe implementations on github, but they use
>> recur to track state and I was hoping there was a cleaner idiomatic way than
>> that.
>>
>> Thanks!
>>
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