Hi,
it might be better to use a simple abstact data type for it like:
-- | Command Type has for all possible actions a contructor
data Command = INIT String String Bool -- ^ Teamname, Version, Goalkeeper or not
| RECONNECT String Integer -- ^ Teamname, Playernum (Unum)
| CATCH Angle
| CHANGEVIEW ViewWidth ViewQuality
| DASH Integer -- ^ Power [-100, 100]
| KICK Integer Angle -- ^ Power [-100,100], direction
| MOVE Double Double -- ^ X, Y Coordinate
| SAY String
| REQUESTSENSEBODY
| REQUESTSCORE
| TURN Angle -- ^ Angle [-180, 180] see 'Direction'
| TURNNECK Angle -- ^ Angle [-90,90]
| BYE
| NOACTION -- ^ this means we do nothing
-- Show instance for Command to create syntactical correct command strings
instance Show Command where
show NOACTION = ""
show c = "(" ++ (concat strlist) ++ ")"
where strlist =
case c of
INIT team ver True -> ["init ", team, " (version ", ver, ") goalie"]
INIT team ver False -> ["init ", team, " (version ", ver, ")"]
RECONNECT team unum -> ["reconnect ", team, " ", show unum]
CATCH dir -> ["catch ", show dir]
CHANGEVIEW width quali -> ["change_view ", show width, show quali]
DASH p -> ["dash ", show p]
KICK p dir -> ["kick ", show p, " ", show dir]
MOVE x y -> ["move ", show x, " ", show y]
SAY msg -> ["say ", msg]
REQUESTSENSEBODY -> ["sense_body"]
REQUESTSCORE -> ["score"]
TURN a -> ["turn ", show a]
TURNNECK a -> ["turn_neck ", show a]
BYE -> ["bye"]
NOACTION -> [""] -- just for compiler
you can just have a [Command] and use show to get the string representation.
As you might guess I have implemented a socker client in haskell allready. I can mail you the code if you want. It is still in the alpha stage, but it can do quite a lot.
Best Regards!
Georg
On Sun, 19 Sep 2004 13:48:53 -0400, Andrew Harris
Hi -
I have another question. I am still working on a soccer server and thought it would be neat to create command objects that had a "toString" method. Then, I was going to keep a list of these command objects and at the right time stringify them and send them to the server. So I created a class with a toString method:
class ServerCommandClass a where toString :: a -> String
And then a few instances:
-- dash command data DashCommand = DashCommand { dashpower :: Double }
instance ServerCommandClass DashCommand where toString c = "(dash " ++ show (dashpower c) ++ ")\n"
-- move command data MoveCommand = MoveCommand { x :: Double, y :: Double }
instance ServerCommandClass MoveCommand where toString c = "(move " ++ show (x c) ++ " " ++ show (y c) ++ ")\n"
The problem is, I am not quite sure how to describe a *list* of command objects where the list could have both DashCommands and MoveCommands in it. Ideally the list could contain both, and then for each item in the list I could call the toString method.
I was reading Simon Thompson's Haskell: The Craft of Functional Programming and I read that Haskell 98 does not support dynamic binding, which (it seems) is what I'm trying to do. Does anyone have a suggestion on an alternative approach?
thanks, -andrew _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
-- ---- Georg Martius, Tel: (034297) 89434 ---- ------- http://www.flexman.homeip.net ---------