-- | -- This module provides a ready to use implementation of `web-routes` for Snap. -- -- The tutorial assumes you have a standard Snap app with an Application.hs and -- Site.hs. -- -- To get going, you'll need to add a few things to Application.hs -- -- @ -- -- Enable a few extensions -- -- \-\- Needed to derive a generic instance for our URL data type -- \{\-\# LANGUAGE DeriveGeneric \#\-\} -- -- \-\- Needed by web-routes -- \{\-\# LANGUAGE FlexibleInstances \#\-\} -- \{\-\# LANGUAGE TypeFamilies \#\-\} -- -- \-\- Paths and params are of type Text. -- import Data.Text (Text) -- -- \-\- Snap.Web.Routes.Types exports everything you need to -- \-\- define your PathInfo and MonadRoute instances. -- import Snap.Web.Routes.Types -- -- \-\- Your URL data type. Deriving a `Generic` instance gives -- \-\- you a `PathInfo` instance for free. -- data AppUrl -- = Count Int -- | Echo Text -- | Paths [Text] -- deriving (Generic) -- -- \-\- Extend your App type to include a routing function. -- data App = App -- { _routeFn :: AppUrl -> [(Text, Maybe Text)] -> Text -- } -- -- \-\- Thanks to the wonders of Generic, an empty instance -- \-\- definition is all we need. Alternately, you can implement -- \-\- toPathSegments and fromPathSegments yourself or use -- \-\- web-routes-th. -- instance PathInfo AppUrl -- -- \-\- Set URL (Handler App App) to your URL data type defined above -- \-\- and askRouteFn must point to the routing function you added to -- \-\- your App. -- instance MonadRoute (Handler App App) where -- type URL (Handler App App) = AppUrl -- askRouteFn = gets _routeFn -- @ -- -- Moving on to Site.hs. -- -- @ -- \-\- Snap.Web.Routes provides routing functions -- import Snap.Web.Routes -- -- \-\- Add your new routes using routeWith -- routes :: [(ByteString, Handler App App ())] -- routes = [ ("", routeWith routeAppUrl) -- , ("", serveDirectory "static") -- ] -- -- \-\- Define handlers for each value constructor in your URL data type. -- routeAppUrl :: AppUrl -> Handler App App () -- routeAppUrl appUrl = -- case appUrl of -- (Count n) -> writeText $ ("Count = " `T.append` (T.pack $ show n)) -- (Echo text) -> echo text -- (Paths ps) -> writeText $ T.intercalate " " ps -- -- \-\- You'll note that these are normal Snap handlers, except they can take -- \-\- values from the value constructor as arguments. This is a lot nicer than -- \-\- having to use getParam. -- echo :: T.Text -> Handler App App () -- echo msg = heistLocal (bindString "message" msg) $ render "echo" -- -- \-\- Add the routing function to your app. -- app :: SnapletInit App App -- app = makeSnaplet "app" "An example snap-web-routes app." Nothing $ do -- addRoutes routes -- return $ App renderRoute -- @ -- -- If you prefixed the routes in routeWith -- -- > ("/prefix", routeWith routeAppUrl) -- -- then use `renderRouteWithPrefix` instead: -- -- > return . App $ renderRouteWithPrefix "/prefix" -- -- If you are having trouble figuring out why a particular request isn't routing -- as expected, try replacing 'routeWith' with 'routeWithDebug'. It'll display -- the available routes, as well as any failed route parses. Just remember that -- it's not suitable for production use. module Snap.Web.Routes ( routeWith , routeWithDebug , renderRoute , renderRouteWithPrefix , showUrl , showUrlParams , urlSplice ) where import Snap.Web.Routes.App import Snap.Web.Routes.Heist import Snap.Web.Routes.Text