oauth2Callback
  :: IAuthBackend u i e b
  => OAuth2Settings u i e b
  -> Handler b (AuthManager u e b) ()
oauth2Callback s = do
  provs <- gets providers
  maybe pass (oauth2Callback' s) =<<
    ((flip M.lookup provs =<<) <$> getParamText "provider")
oauth2Callback
  :: IAuthBackend u i e b
  => OAuth2Settings u i e b
  -> Handler b (AuthManager u e b) ()
oauth2Callback s = do
  provs <- gets providers
  maybe pass (oauth2Callback' s) =<<
    ((flip M.lookup provs =<<) <$> getParamText "provider")
oauth2Callback s = do
  provs <- gets providers
  maybe pass (oauth2Callback' s) =<<
    ((flip M.lookup provs =<<) <$> getParamText "provider")