Re: [Haskell-cafe] GHCi and State
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 On 6/25/10 05:07 , corentin.dup...@ext.mpsa.com wrote: > Instead of writing my own reader/interpreter, i'd like to use GHC to compil > them on the fly, and then add them to the current "legislation". > What would you suggest me to do that? Any pointers? GHC API. This is likely biting off more than you want to chew, though; it'll probably be easier to write your own interpreter, > 2. For now, the game is more or less playable in GHCi. But my concern is: > When you use GHCi, you are in the IO monad, right? How to had state to this > monad? runStateT nomicGame initialState :: IO (a,GameState) -- nomicGame :: StateT GameState IO a -- initialState :: GameState -- use evalStateT instead of runStateT if all you want is the result, -- or execStateT if all you want is the final state. -- if you want neither: -- _ <- runStateT ... > I would like that the player can compose his rule in GHCi, and when he is > done, he can submit it in GHCi with something like: > > *Nomic> submitRule > > And then the game takes the rule, possibly modify the current legislation, > and give the hand back to GHCi. > So the "current legislation" has to be a state of the GHCi's loop. Is this > possible at all? Use an IORef to contain the state, if you really want to go this way. I wouldn't; take a look at the lambdabot source for the pitfalls of passing arbitrary user-provided code to GHCi (or GHC API), and how to avoid them. (In particular, if you're using GHC to parse your rules, what stops the user code from mangling the GameState on you?) - -- brandon s. allbery [linux,solaris,freebsd,perl] allb...@kf8nh.com system administrator [openafs,heimdal,too many hats] allb...@ece.cmu.edu electrical and computer engineering, carnegie mellon university KF8NH -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.10 (Darwin) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAkwkdygACgkQIn7hlCsL25WfhgCgo2qfkoA0yBaXsrjQNT+xePSb vJMAnjLQnOtaByKXSsFvLuclcFt7vhEg =jnru -END PGP SIGNATURE- ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] GHCi and State
On 25.06.10 12:07, corentin.dup...@ext.mpsa.com wrote: 2. For now, the game is more or less playable in GHCi. But my concern is: When you use GHCi, you are in the IO monad, right? How to had state to this monad? I would like that the player can compose his rule in GHCi, and when he is done, he can submit it in GHCi with something like: *Nomic> submitRule You can store a set of rules in IORef or another IO-mutable type. I think "you are in the IO monad" is pretty vague. Obviously, GHCi runs pure computations also. -- Best regards, Roman Beslik. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] GHCi and State
hi, On 25.06.2010 11:07, corentin.dup...@ext.mpsa.com wrote: Another couple of reflexions (sorry for monopolizing): 1. Since i am making a Nomic game, players will have to submit rules. These rules will be written in a sub-set of haskell. Instead of writing my own reader/interpreter, i'd like to use GHC to compil them on the fly, and then add them to the current "legislation". What would you suggest me to do that? Any pointers? check out hint, a nice wrapper around the ghc api [1]. have fun martin [1]: http://hackage.haskell.org/package/hint 2. For now, the game is more or less playable in GHCi. But my concern is: When you use GHCi, you are in the IO monad, right? How to had state to this monad? I would like that the player can compose his rule in GHCi, and when he is done, he can submit it in GHCi with something like: *Nomic> submitRule And then the game takes the rule, possibly modify the current legislation, and give the hand back to GHCi. So the "current legislation" has to be a state of the GHCi's loop. Is this possible at all? submitRule would have a type more or less like that (GameState contains the legislation): submitRule :: Rule -> StateT GameState IO () Thanks for your attention! I know this is a bit confused! Best, Corentin ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] GHCi and State
On 25.06.2010 11:07, corentin.dup...@ext.mpsa.com wrote: 2. For now, the game is more or less playable in GHCi. But my concern is: When you use GHCi, you are in the IO monad, right? How to had state to this monad? I would like that the player can compose his rule in GHCi, and when he is done, he can submit it in GHCi with something like: *Nomic> submitRule You can use IORefs for this purpose. However you have to initialize the IORef before running the first action and then you must pass the IORef to every subsequent action. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] GHCi and State
Hi Corentin, Interesting. Have you thought about following the example of XMonad instead? The analogy could goes as follows: XMonad's configuration file (~/.xmonad/xmonad.hs) <=> Your rules. XMonad's state <=> Your state. Editing the config file <=> Changing the rules. Of course you normally edit the config file while XMonad is running, and in theory XMonad could do funny things to your Emacs, i.e. require you to vote before letting any edit-command through. When you change your configuration file, you send a specific key-sequence to XMonad (Alt-q is the default), and XMonad serializes it's state into a string, compiles the new config file, and then replaces itself with the new instance, handing over it's state. No mutable-state-in-IO trickery necessary. Matthias. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Réf. : Re: [Haskell-cafe] GHCi and State
Hello,
thank you for your answer.
Brandon,
Indeed I think that i should write my own interpreter for a first version
of the game. I would be very instructive.
But then, i'd like that the player could use the full power of Haskell to
write their own rules during game play.
Neat functions like map, filter etc. could be used by the player to write
rules.
Perhaps Hint is good for me.
> take a look at the lambdabot source for the pitfalls of passing
>arbitrary user-provided code to GHCi (or GHC API), and how to avoid them.
>(In particular, if you're using GHC to parse your rules, what stops the
user
>code from mangling the GameState on you?)
The code passed is not that arbitrary, it must have type "Rule".
This type would enforce certain constructions, and actions...
Roman,
for GHCi, i will try an IORef. Too bad i allready coded it using "StateT
GameState IO ()" extensively through the code ;)
Corentin
Brandon S
Allbery KF8NH
haskell-cafe@haskell.org
Envoyé par : cc
haskell-cafe-bou
n...@haskell.orgObjet
Re: [Haskell-cafe] GHCi and State
25/06/2010 11:30
-BEGIN PGP SIGNED MESSAGE-
Hash: SHA1
On 6/25/10 05:07 , corentin.dup...@ext.mpsa.com wrote:
> Instead of writing my own reader/interpreter, i'd like to use GHC to
compil
> them on the fly, and then add them to the current "legislation".
> What would you suggest me to do that? Any pointers?
GHC API. This is likely biting off more than you want to chew, though;
it'll probably be easier to write your own interpreter,
> 2. For now, the game is more or less playable in GHCi. But my concern is:
> When you use GHCi, you are in the IO monad, right? How to had state to
this
> monad?
runStateT nomicGame initialState :: IO (a,GameState)
-- nomicGame :: StateT GameState IO a
-- initialState :: GameState
-- use evalStateT instead of runStateT if all you want is the result,
-- or execStateT if all you want is the final state.
-- if you want neither:
-- _ <- runStateT ...
> I would like that the player can compose his rule in GHCi, and when he is
> done, he can submit it in GHCi with something like:
>
> *Nomic> submitRule
>
> And then the game takes the rule, possibly modify the current
legislation,
> and give the hand back to GHCi.
> So the "current legislation" has to be a state of the GHCi's loop. Is
this
> possible at all?
Use an IORef to contain the state, if you really want to go this way. I
wouldn't; take a look at the lambdabot source for the pitfalls of passing
arbitrary user-provided code to GHCi (or GHC API), and how to avoid them.
(In particular, if you're using GHC to parse your rules, what stops the
user
code from mangling the GameState on you?)
- --
brandon s. allbery [linux,solaris,freebsd,perl] allb...@kf8nh.com
system administrator [openafs,heimdal,too many hats] allb...@ece.cmu.edu
electrical and computer engineering, carnegie mellon university KF8NH
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Re: Réf. : Re: [Haskell-cafe] GHCi and State
Hi Corentin, corentin.dup...@ext.mpsa.com schrieb: for GHCi, i will try an IORef. Too bad i allready coded it using "StateT GameState IO ()" extensively through the code ;) That shouldn't be a problem, you could switch back and forth in submitRule, approximately like this: startGame :: IO (Rule -> IO ()) startGame = do gameState <- newIORef initialState return (\rule -> wrapStateT (submitRule rule) gameState) wrapStateT :: StateT s IO a -> IORef s -> IO a wrapStateT action ref = do state <- readIORef ref (answer, state) <- runStateT action state writeIORef ref state return answer Now you can start a game with mySubmitRule <- startGame and use mySubmitRule at the ghci prompt afterwards. Tillmann ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
