yes, you could do this with a state monad, though how the results will
end up looking will depend on the particular monad implementation you
go for.
On Mon, Feb 11, 2013 at 12:10 PM, JvJ <kfjwhee...@gmail.com> wrote:
> I'm writing a simple game engine in Clojure, and each game object supplies
> its own unique update function, which takes the original object (a map of
> properties) and returns an updated version. However, writing the updates is
> somewhat cumbersome because each line of code has to return either the
> original or updated object. I'd like to see if I can clean up this code,
> possibly by using monads (which I don't understand very well). Does anyone
> have any advice? Thanks (Code examples below)
>
> The pseudocode for what i want to do looks something like this:
>
> if left key is held
> g.position += [-10 0]
> if right key is held
> g.position += [10 0]
> if up key is held
> g.position += [0 -10]
> if down key is held
> g.position += [0 10]
> if q is pressed
> fire event {:type :dialogue, :text "Hello"}
> if space is pressed
> g.switchstate(:s2)
>
>
> But the code I ended up writing is this mess:
>
>
> (fn [g]
> (-> g
> (#(if (@*keys-held* :left)
> (update-in % [:position] v+ [-10 0])
> %))
> (#(if (@*keys-held* :right)
> (update-in % [:position] v+ [10 0]) %))
> (#(if (@*keys-held* :up)
> (update-in % [:position] v+ [0 -10]) %))
> (#(if (@*keys-held* :down)
> (update-in % [:position] v+ [0 10]) %))
> (#(if (@*keys-pressed* \q)
> (do (fire-event {:type :dialogue
> :text "Hello!"})
> %)
> %))
> (#(if (@*keys-pressed* :space)
> (do (comment (println "spaced!"))
> (switch-state % :s2)) %))))
>
> --
> --
> You received this message because you are subscribed to the Google
> Groups "Clojure" group.
> To post to this group, send email to clojure@googlegroups.com
> Note that posts from new members are moderated - please be patient with your
> first post.
> To unsubscribe from this group, send email to
> clojure+unsubscr...@googlegroups.com
> For more options, visit this group at
> http://groups.google.com/group/clojure?hl=en
> ---
> You received this message because you are subscribed to the Google Groups
> "Clojure" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to clojure+unsubscr...@googlegroups.com.
> For more options, visit https://groups.google.com/groups/opt_out.
>
>
--
Ben Wolfson
"Human kind has used its intelligence to vary the flavour of drinks,
which may be sweet, aromatic, fermented or spirit-based. ... Family
and social life also offer numerous other occasions to consume drinks
for pleasure." [Larousse, "Drink" entry]
--
--
You received this message because you are subscribed to the Google
Groups "Clojure" group.
To post to this group, send email to clojure@googlegroups.com
Note that posts from new members are moderated - please be patient with your
first post.
To unsubscribe from this group, send email to
clojure+unsubscr...@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/clojure?hl=en
---
You received this message because you are subscribed to the Google Groups
"Clojure" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to clojure+unsubscr...@googlegroups.com.
For more options, visit https://groups.google.com/groups/opt_out.
