If you use hash-maps, or a struct-map as the basis of your individual,
you can just make a key 'fitness', and store the once-calculated
fitness in there.
I'm not sure how, but it might be possible that at the creation of
your animals, you assign the key 'fitness' a basic function that upon
being accessed replaces itself with its outcome. I would be interested
in seeing that coded. It would be a very neat way to do what you want.
proof of concept, which is not going to win a beaty contest.
user=> (def myhost (hash-map :c 15 :b 3 :a (fn [hostname] (assoc
hostname :a (* (hostname :b) (hostname :c))))))
#'user/myhost
user=> myhost
{:a #<user$fn__35 user$fn_...@d85cc>, :b 3, :c 15}
user=> (def myhost ((myhost :a) myhost))
#'user/myhost
user=> myhost
{:a 45, :b 3, :c 15}
user=>
On Mar 4, 6:27 pm, Meikel Brandmeyer <m...@kotka.de> wrote:
> Hi,
>
> Am 04.03.2009 um 18:21 schrieb Dan:
>
> > How can I have my fitness computation be triggered on first access
> > and reused afterward?
>
> Maybe you can use a Delay.
>
> {:fitness (delay (compute-my-fitness))}
>
> And when you access the value use force.
>
> (-> my-thing :fitness force)
>
> The first time it is accessed, the value is calculated.
> Afterwards the cached value is returned. If you don't
> use the value of interim stages, it is not calculated.
>
> Sincerely
> Meikel
>
> <commercial>
> If you use maps as above I also have a lazy-map
> package, which evaluates the value of key only
> in case it is really accessed.
>
> http://bitbucket.org/kotarak/lazymap
> </commercial>
>
> smime.p7s
> 5KViewDownload
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