Language GET param and cookie; simple i18n example

Yesod/Definitions.hs

@@ -25,6 +25,7 @@ module Yesod.Definitions
     , authCookieName
     , authDisplayName
     , encryptedCookies
+    , langKey
     ) where
 
 import qualified Hack
@@ -79,3 +80,6 @@ authDisplayName = "DISPLAY_NAME"
 
 encryptedCookies :: [String]
 encryptedCookies = [authDisplayName, authCookieName]
+
+langKey :: String
+langKey = "_LANG"

Yesod/Yesod.hs

@@ -103,9 +103,14 @@ toHackApp'' y tg env = do
         rr = cs env
     res <- runHandler handler errorHandler rr y tg types
     let acceptLang = lookup "Accept-Language" $ Hack.http env
-    -- FIXME get languages from a cookie as well
     let langs = maybe [] parseHttpAccept acceptLang
-    responseToHackResponse langs res
+        langs' = case lookup langKey $ rawCookies rr of
+                    Nothing -> langs
+                    Just x -> x : langs
+        langs'' = case lookup langKey $ rawGetParams rr of
+                     Nothing -> langs'
+                     Just x -> x : langs'
+    responseToHackResponse langs'' res
 
 httpAccept :: Hack.Env -> [ContentType]
 httpAccept = map TypeOther . parseHttpAccept . fromMaybe ""

examples/i18n.hs

@@ -0,0 +1,34 @@
+{-# LANGUAGE QuasiQuotes #-}
+import Yesod
+import Yesod.Constants
+import Hack.Handler.SimpleServer
+
+data I18N = I18N
+
+instance Yesod I18N where
+    handlers = [$resources|
+/:
+    Get: homepage
+/set/$lang:
+    Get: setLang
+|]
+
+homepage = return Hello
+
+setLang lang = do
+    addCookie 1 langKey lang
+    redirect "/"
+    return ()
+
+data Hello = Hello
+
+instance HasReps Hello where
+    reps = [(TypeHtml, const $ return $ Content $ return . cs . content)]
+      where
+        content [] = "Hello"
+        content ("he":_) = "שלום"
+        content ("es":_) = "Hola"
+        content (_:rest) = content rest
+
+
+main = putStrLn "Running..." >> run 3000 (toHackApp I18N)