Routes.elm

parseToken : Parser (Maybe Token -> a) a
parseToken =
    custom "ACCESS_TOKEN" <|
        \segment ->
            case String.split "&" segment |> List.map (String.split "=") of
                [ [ "access_token", accessToken ]
                 , [ "expires_in", expires ]
                 , [ "token_type", type_ ]
                 , [ "state", state ]
                 , [ "id_token", idToken ] ] ->
                    case String.toInt expires of
                        Ok int -> 
                            Ok <| Just <| Auth0Token accessToken idToken type_ int                          
                        Err e ->
                            Err "Missing expires_in"
                _ ->
                    Err "Not an access token"