beginner question
Dennis Haupt
Hash: SHA1
in java, i would start coding a game with a loop like this:
while (true) {
logic();
render();
}
i would store the current state of the world in an object containing
the complete data of the whole game and update its values in each
iteration.
how would i do this in clojure?
the outer loop could look like
(def next [oldstate] (....)) <- input = current game, return value =
next iteration
(loop [world initalState] (recur (next world))) // <- the loop
but how would be world look like? the "best" (most trivial) thing that
i could think of is for it to be a map which is passed along several
transform functions, for example
(def playerHealthRegen [world] (...)) <- input = world (a map), output
= a new map with a new entry at key "playerhealth"
each function would then return a slightly modified version of the
world, and at the end, i'll have my completely new state.
is that about right? or is there a completely different way i overlooked?
- --
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Alan Malloy
render (iterate next-state start-state))
John
=>(defn step [world-state])
(-> world-state
update-health
update-physics
update-ai))
where e.g. update-health is something like
=>(defn update-health [world-state]
(update-in world-state [:player :health] inc))
then yeah just iterate or loop/recur
=>(take 20 (iterate step init-state))
this is the purely functional way of doing it.
Matt Hoyt
From: Dennis Haupt <d.ha...@googlemail.com>
To: clo...@googlegroups.com
Sent: Saturday, September 24, 2011 2:36 PM
Subject: beginner question
You received this message because you are subscribed to the Google
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Dennis Haupt
Hash: SHA1
i assumed my game to be so much fun that no one would ever want to
stop playing it.
Am 24.09.2011 22:26, schrieb Matt Hoyt:
> You need a check in the loop to see if the player wants to end the
> game. Clojure doesn't have a break statement like Java so you
> created a infinite loop that will never end. To make sure the game
> ends you need to have a base case. Example of a main game loop in
> clojure:
>
> (loop [game-state initial-state] (if (game-ends? game-state)
> (close-game game-state) (recur (render (logic game-state)))))
>
> You should also look into records to store the game's state.
> Records are faster than hash maps and you have polymorphism with
> protocols.
if i remember correctly, deftype = map, defrecord = class?
how does "assoc" work on records?
Be
> careful of the lazy functions in clojure like map. It will only
> execute when you ask a value for it.
render should do that
>
> Matt Hoyt
> ------------------------------------------------------------------------
>
>
*From:* Dennis Haupt <d.ha...@googlemail.com>
> *To:* clo...@googlegroups.com *Sent:* Saturday, September 24, 2011
> 2:36 PM *Subject:* beginner question
>
> in java, i would start coding a game with a loop like this: while
> (true) { logic(); render(); }
>
> i would store the current state of the world in an object
> containing the complete data of the whole game and update its
> values in each iteration.
>
> how would i do this in clojure?
>
> the outer loop could look like (def next [oldstate] (....)) <-
> input = current game, return value = next iteration
>
> (loop [world initalState] (recur (next world))) // <- the loop
>
> but how would be world look like? the "best" (most trivial) thing
> that i could think of is for it to be a map which is passed along
> several transform functions, for example
>
> (def playerHealthRegen [world] (...)) <- input = world (a map),
> output = a new map with a new entry at key "playerhealth"
>
> each function would then return a slightly modified version of the
> world, and at the end, i'll have my completely new state.
>
> is that about right? or is there a completely different way i
> overlooked?
>
>
> -- You received this message because you are subscribed to the
> Google Groups "Clojure" group. To post to this group, send email to
> clo...@googlegroups.com <mailto:clo...@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+u...@googlegroups.com
> <mailto:unsub...@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
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> clo...@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
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> group at http://groups.google.com/group/clojure?hl=en
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Matt Hoyt
Subject: Re: beginner question
> <mailto:unsub...@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 post to this group, send email to
> clo...@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
Dennis Haupt
Hash: SHA1
mutable? like in "not functional"?
*reading*
Am 24.09.2011 23:11, schrieb Matt Hoyt:
> Both of them are java objects. Records has more default
> functionality like implementing equals, hashcode, etc. You can
> read more about the differences here: http://clojure.org/datatypes
>
> assoc for records sets the value of the property for the record.
>
> Matt Hoyt
> ------------------------------------------------------------------------
>
>
*From:* Dennis Haupt <d.ha...@googlemail.com>
> *To:* clo...@googlegroups.com *Sent:* Saturday, September 24, 2011
> 3:54 PM *Subject:* Re: beginner question
>
> i assumed my game to be so much fun that no one would ever want to
> stop playing it.
>
> Am 24.09.2011 22:26, schrieb Matt Hoyt:
>> You need a check in the loop to see if the player wants to end
>> the game. Clojure doesn't have a break statement like Java so
>> you created a infinite loop that will never end. To make sure
>> the game ends you need to have a base case. Example of a main
>> game loop in clojure:
>
>> (loop [game-state initial-state] (if (game-ends? game-state)
>> (close-game game-state) (recur (render (logic game-state)))))
>
>> You should also look into records to store the game's state.
>> Records are faster than hash maps and you have polymorphism with
>> protocols.
>
> if i remember correctly, deftype = map, defrecord = class? how does
> "assoc" work on records?
>
>
> Be
>> careful of the lazy functions in clojure like map. It will only
>> execute when you ask a value for it.
>
> render should do that
>
>
>> Matt Hoyt
>> ------------------------------------------------------------------------
>
>>
>
> *From:* Dennis Haupt <d.ha...@googlemail.com
> <mailto:d.ha...@googlemail.com>>
>> *To:* clo...@googlegroups.com <mailto:clo...@googlegroups.com>
> *Sent:* Saturday, September 24, 2011
>> 2:36 PM *Subject:* beginner question
>
>> in java, i would start coding a game with a loop like this:
>> while (true) { logic(); render(); }
>
>> i would store the current state of the world in an object
>> containing the complete data of the whole game and update its
>> values in each iteration.
>
>> how would i do this in clojure?
>
>> the outer loop could look like (def next [oldstate] (....)) <-
>> input = current game, return value = next iteration
>
>> (loop [world initalState] (recur (next world))) // <- the loop
>
>> but how would be world look like? the "best" (most trivial)
>> thing that i could think of is for it to be a map which is passed
>> along several transform functions, for example
>
>> (def playerHealthRegen [world] (...)) <- input = world (a map),
>> output = a new map with a new entry at key "playerhealth"
>
>> each function would then return a slightly modified version of
>> the world, and at the end, i'll have my completely new state.
>
>> is that about right? or is there a completely different way i
>> overlooked?
>
>
>> -- You received this message because you are subscribed to the
>> Google Groups "Clojure" group. To post to this group, send email
>> to clo...@googlegroups.com <mailto:clo...@googlegroups.com>
> <mailto:clo...@googlegroups.com <mailto:clo...@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+u...@googlegroups.com
>> <mailto:unsub...@googlegroups.com>
>> <mailto:unsub...@googlegroups.com
> <mailto:unsub...@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 post to this group, send email
>> to clo...@googlegroups.com <mailto:clo...@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+u...@googlegroups.com
> <mailto:unsub...@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
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>
>
> -- You received this message because you are subscribed to the
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Dennis Haupt
Hash: SHA1
the website says:
deftype supports mutable fields, defrecord does not
so deftype seems to be what would be a java bean with simple
properties in java
Am 24.09.2011 23:11, schrieb Matt Hoyt:
> Both of them are java objects. Records has more default
> functionality like implementing equals, hashcode, etc. You can
> read more about the differences here: http://clojure.org/datatypes
>
> assoc for records sets the value of the property for the record.
>
> Matt Hoyt
> ------------------------------------------------------------------------
>
>
*From:* Dennis Haupt <d.ha...@googlemail.com>
> *To:* clo...@googlegroups.com *Sent:* Saturday, September 24, 2011
> 3:54 PM *Subject:* Re: beginner question
>
> i assumed my game to be so much fun that no one would ever want to
> stop playing it.
>
> Am 24.09.2011 22:26, schrieb Matt Hoyt:
>> You need a check in the loop to see if the player wants to end
>> the game. Clojure doesn't have a break statement like Java so
>> you created a infinite loop that will never end. To make sure
>> the game ends you need to have a base case. Example of a main
>> game loop in clojure:
>
>> (loop [game-state initial-state] (if (game-ends? game-state)
>> (close-game game-state) (recur (render (logic game-state)))))
>
>> You should also look into records to store the game's state.
>> Records are faster than hash maps and you have polymorphism with
>> protocols.
>
> if i remember correctly, deftype = map, defrecord = class? how does
> "assoc" work on records?
>
>
> Be
>> careful of the lazy functions in clojure like map. It will only
>> execute when you ask a value for it.
>
> render should do that
>
>
>> Matt Hoyt
>> ------------------------------------------------------------------------
>
>>
>
> *From:* Dennis Haupt <d.ha...@googlemail.com
> <mailto:d.ha...@googlemail.com>>
>> *To:* clo...@googlegroups.com <mailto:clo...@googlegroups.com>
> *Sent:* Saturday, September 24, 2011
>> 2:36 PM *Subject:* beginner question
>
>> in java, i would start coding a game with a loop like this:
>> while (true) { logic(); render(); }
>
>> i would store the current state of the world in an object
>> containing the complete data of the whole game and update its
>> values in each iteration.
>
>> how would i do this in clojure?
>
>> the outer loop could look like (def next [oldstate] (....)) <-
>> input = current game, return value = next iteration
>
>> (loop [world initalState] (recur (next world))) // <- the loop
>
>> but how would be world look like? the "best" (most trivial)
>> thing that i could think of is for it to be a map which is passed
>> along several transform functions, for example
>
>> (def playerHealthRegen [world] (...)) <- input = world (a map),
>> output = a new map with a new entry at key "playerhealth"
>
>> each function would then return a slightly modified version of
>> the world, and at the end, i'll have my completely new state.
>
>> is that about right? or is there a completely different way i
>> overlooked?
>
>
>> -- You received this message because you are subscribed to the
>> Google Groups "Clojure" group. To post to this group, send email
>> to clo...@googlegroups.com <mailto:clo...@googlegroups.com>
> <mailto:clo...@googlegroups.com <mailto:clo...@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+u...@googlegroups.com
>> <mailto:unsub...@googlegroups.com>
>> <mailto:unsub...@googlegroups.com
> <mailto:unsub...@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 post to this group, send email
>> to clo...@googlegroups.com <mailto:clo...@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+u...@googlegroups.com
> <mailto:unsub...@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
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>
>
> -- You received this message because you are subscribed to the
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Stefan Kamphausen
regarding the writing of a game in Clojure, I think http://codethat.wordpress.com/2011/09/10/writing-tetris-in-clojure/ is a good post to read.
Regards,
Stefan
Stuart Halloway
>
> deftype supports mutable fields, defrecord does not
>
> so deftype seems to be what would be a java bean with simple
> properties in java
Nope. :-)
Domain information should use defrecord, and should never be mutable. This is the closest thing to a Java bean, but is radically different in being (1) immutable, (2) persistent, and (3) accessible generically as a map. Game state would modeled with defrecord.
deftype is for things like custom data structures. In a Clojure-in-Clojure implementation, deftype would be used to implement maps, vectors, and lists. deftype's mutation ability would be used to implement transients.
Stu
Dennis Haupt
Hash: SHA1
Am 25.09.2011 14:00, schrieb Stuart Halloway:
>> the website says:
>>
>> deftype supports mutable fields, defrecord does not
>>
>> so deftype seems to be what would be a java bean with simple
>> properties in java
>
> Nope. :-)
>
> Domain information should use defrecord, and should never be
> mutable. This is the closest thing to a Java bean, but is radically
> different in being (1) immutable, (2) persistent, and (3)
> accessible generically as a map. Game state would modeled with
> defrecord.
what's the difference between persistent and immutable?
>
> deftype is for things like custom data structures. In a
> Clojure-in-Clojure implementation, deftype would be used to
> implement maps, vectors, and lists. deftype's mutation ability
> would be used to implement transients.
>
> Stu
>
>
- --
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Stuart Halloway
See http://en.wikipedia.org/wiki/Persistent_data_structure, which now has a nice shout out to Clojure.
Stu
Phil Hagelberg
On Sep 25, 2011 6:12 AM, "Dennis Haupt" <d.ha...@googlemail.com> wrote:
> what's the difference between persistent and immutable?
I have written a summary of this distinction on my blog: http://technomancy.us/132
Hope that helps.
-Phil
Dennis Haupt
Hash: SHA1
so there is no difference.
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Dennis Haupt
Hash: SHA1
so persistent is immutable + x like "car" is "movable" + x. it doesn't
make sense to ask what the difference is.
Am 25.09.2011 18:59, schrieb Phil Hagelberg:
>
> On Sep 25, 2011 6:12 AM, "Dennis Haupt" <d.ha...@googlemail.com
> <mailto:d.ha...@googlemail.com>> wrote:
>> what's the difference between persistent and immutable?
>
> I have written a summary of this distinction on my blog:
> http://technomancy.us/132
>
> Hope that helps.
>
> -Phil
>
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Andy Fingerhut
For example, imagine an immutable array that, unlike Clojure's vector data structure, implemented "conj" by copying the entire array into a new one with the original elements plus the new one. Immutable, but the performance characteristics are abysmal.
As a more subtle example, imagine an immutable array that, unlike Clojure's vector data structure, let you "update" arbitrary elements, and did not copy the entire array, but created an imbalanced tree of vector indices that had their values "updated". A lookup in this augmented data structure would require first looking through the imbalanced tree for the index, to see if it had been modified, and only if it failed to find it in the tree would it be looked up in the original array. Immutable, but not persistent in the sense that it maintains the performance characteristics of the original data structure -- the augmented/updated data structure has slow access times than the original.
Andy