Hi Erik, yes you're right, I'm experimenting with an IORef now (a TVar would be a better idea). I also tried the idea expressed here, to keep the state: https://groups.google.com/forum/?fromgroups=#!msg/happs/_JSpaJKub0k/oa0K01IBlh0J But without success so far. The server is returning me the state in the Response type but I cannot manage to reinject it for the next call :)
Best, Corentin On Thu, Aug 30, 2012 at 9:47 PM, Erik Hesselink <[email protected]> wrote: > The way you wrote it, you run the state transformer once for each > request. So the state will be available within a single request, but > not between requests. If you want to persist state between requests, > you can use one the the mutable variables available (TVar or MVar are > good choices; IORefs also work, but you have to take care about > concurrency, using e.g. atomicModifyIORef). Create them before calling > simpleHTTP, then pass them in to use them in your handler. You can put > them in a ReaderT to avoid passing them, if you want. > > Another choice is to use something like a database or the file system > for persistent state. Databases usually handle most concurrency > problems for you, while file systems don't. > > Regards, > > Erik > > On Thu, Aug 30, 2012 at 7:29 PM, Corentin Dupont > <[email protected]> wrote: > > Hi all, > > I'm trying to make a web server that manages its own state. The user can > > issue commands that modifies the state. > > I did like below but unfortunatly the state is not keep after a command > is > > issued... > > What is the right way to do it? Is there any example sites with an > internal > > state with happstack? > > > > data Game = (the state of my game) > > type NomicServer = ServerPartT (StateT Game IO) > > > > launchWebServer :: Game -> IO () > > launchWebServer initialState = do > > putStrLn "Starting web server...\nTo connect, drive your browser to > > \"http://localhost:8000/Login\""; > > d <- getDataDir > > simpleHTTP' unpackStateT nullConf $ server d > > > > > > server :: FilePath -> ServerPartT (StateT Game IO) Response > > server d sh = mconcat [fileServe [] d, do > > decodeBody (defaultBodyPolicy "/tmp/" > > 4096 4096 4096) > > html <- implSite " > http://localhost:8000/"; > > "" nomicSite > > return $ toResponse html] > > > > unpackStateT:: Game -> UnWebT (StateT Game IO) Response -> UnWebT IO > > Response > > unpackStateT g w = evalStateT w g > > > > --handler for web routes > > nomicSite :: Site PlayerCommand (NomicServer Html) > > nomicSite = setDefault (Noop 0) Site { > > handleSite = \f url -> unRouteT (routedNomicCommands url) f > > , formatPathSegments = \u -> (toPathSegments u, []) > > , parsePathSegments = parseSegments fromPathSegments > > } > > > > Thanks a lot, > > Corentin > > _______________________________________________ > > Haskell-Cafe mailing list > > [email protected] > > http://www.haskell.org/mailman/listinfo/haskell-cafe > > >
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