[web-devel] ANNOUNCE: wai-routes-0.1

Anupam Jain ajnsit at gmail.com
Fri Jan 13 18:23:25 CET 2012


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.


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

Anupam Jain

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