On Fri, Jan 13, 2012 at 7:23 PM, Anupam Jain wrote:

Hi,

I couldn't find any library that provides typesafe URLs for plain Wai applications so I modified the code in Yesod.Dispatch (yesod-core) and created wai-routes. This is my first time writing TH code so I stuck to "tweaking" the existing functionality.

http://hackage.haskell.org/package/wai-routes

Currently it allows you to define type safe URLs in a manner similar to Yesod. It also provides Middleware to easily insert dispatching into your application.

A sample application that provides a JSON API (using aeson) -

============================================    -- A useful type synonym    type UserId = Text

   -- Define the JSON instance    data User = User { name::Text, uid:: UserId } deriving (Show, Read, Eq)    instance ToJSON User where      toJSON x = object [ "name" .= (name x), "uid" .= (uid x) ]

   -- Define the handlers    getUserR :: UserId -> Application    getUserR uid _req =      return $ responseLBS statusOK headers json      where user = User { name = "Anon Amos", uid = uid }            json = encode user            headers = [("Content-Type", "application/json")]

   getUsersR :: Application    getUsersR _req =      return $ responseLBS statusOK headers json      where userids = (["anon","john","jane"]::[Text])            json = encode userids            headers = [("Content-Type", "application/json")]

   -- Generate the routing datatype and the Route instance    -- The type generated will be named "UserRoute"    mkRoute "User" [parseRoutes|      /users UsersR GET      /user/#UserId UserR GET    |]

   -- Now you can use dispatch function (passing it your route datatype)    main :: IO ()    main = run 8080 $ dispatch (undefined::UserRoute) $ staticApp defaultFileServerSettings ============================================

Thanks, Anupam Jain

Very cool! You might want to look at the code in Yesod 0.10 (on the Github repo), which has a much more efficient dispatch mechanism. The yesod-routes package in there is not actually dependent on Yesod in any way; instead, all of Yesod depends on it. That package itself may be 95% of what you're looking for in wai-routes. Michael