Added permissionDenied function

Yesod/Handler.hs

@@ -27,6 +27,7 @@ module Yesod.Handler
       -- * Special handlers
     , redirect
     , notFound
+    , permissionDenied
       -- * Setting headers
     , addCookie
     , deleteCookie
@@ -206,6 +207,9 @@ redirect = errorResult . Redirect
 notFound :: Handler yesod a
 notFound = errorResult NotFound
 
+permissionDenied :: Handler yesod a
+permissionDenied = errorResult PermissionDenied
+
 ------- Headers
 -- | Set the cookie on the client.
 addCookie :: Int -- ^ minutes to timeout