Adds cookie-based session management to simple Controllers. To add to an application, declare the Controller setting's type an instance of HasSession, and wrap routes with withSession. For example:

data AppSettings = ...

instance HasSession AppSettings where
  ...

controllerApp settings $ withSessions $ do
  routeName \"posts\" $ ...

Then, in your controllers you can seemlessly get and set keys from the session:

get "/profile" $ do
  muserId <- sessionLookup "current_user_id"
  case muserIf of
    Nothing -> respond $ redirectTo "/login"
    Just userId -> [handle request]