[Cs254f11] Fwd: Help me fix this loop

[Jack Laxson]

---------- Forwarded message ----------
From: Jack L. <jackjrabbit at gmail.com>
Date: Tue, Oct 11, 2011 at 7:58 PM
Subject: Re: [Cs254f11] Help me fix this loop
To: Maxwell William Fair Levit <mwl10 at hampshire.edu>


Running the second loop without the last bit works, e.g. ...

(loop [c 1 x (rand-int 19) y (rand-int 19)]
 (if (and (< c 3) (zero? (get @board x y)))
   (place-peice x y (if (even? x) 1 2))
   (recur c (rand-int 19) (rand-int 19)))
 )

Lists all the positions but they're all 0. :)

Jack

On Tue, Oct 11, 2011 at 7:13 PM, Maxwell William Fair Levit <
mwl10 at hampshire.edu> wrote:

>
>
> Hey all, I'm writing code that takes turns placing black and white (1 and
> 2)
> pieces on a Go board. I'm running into trouble with the loop that is
> supposed
> to actually place a bunch of pieces.
>
> (def board
>  (atom
>    (zipmap
>      (reduce concat
>              (for [y (range 19)]
>                (map vector (repeat 19 y )
>                     (for [x (range 19)] x))))
>      (vec (repeat 361 0)))))
>
> ;; defines a 19x19 board with all 361 entires set to 0.
>
>
> (defn place-peice
>  [x y z]
>  (swap! board update-in [[x y]] (fn [j] z) ))
>
> ;;Sets the value of the space with coordinates [x y] to z.
>
> (loop [c 1 x (rand-int 19) y (rand-int 19)]
>  (if (and (< c 3) (zero? (get @board x y)))
>    (do (place-peice x y (if (even? x) 1 2))
>        (recur (inc c) (rand-int 19) (rand-int 19)))
>    (recur c (rand-int 19) (rand-int 19))))
>
> This just crashes clooj, presumably because its going infinitely, since I
> set
> the number of iterations low enough that it shouldn't just be an efficiency
> issue.
>
> The other setup I had which gave me a "Must recur from tail position"
> error. was
> this.
>
>
>
> (loop [c 1 x (rand-int 19) y (rand-int 19)]
>  (if (and (< c 3) (zero? (get @board x y)))
>    (place-peice x y (if (even? x) 1 2))
>    (recur c (rand-int 19) (rand-int 19)))
>  (recur (inc c) (rand-int 19) (rand-int 19)))
>
> Can someone tell me why these don't work and/or how to fix them?
>
>
> Thanks,
>
> -Max
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