template<typename T>
struct function_traits;

template<typename R, typename ...Args>
struct function_traits<std::function<R(Args...)>>
{
    static const size_t nargs = sizeof...(Args);

    typedef R result_type;

    template <size_t i>
    struct arg
    {
        typedef typename std::tuple_element<i, std::tuple<Args...>>::type type;
    };
};

template <Filter T, Filter U>
auto addToPipe(T&& left, U&& right)
{
    return [left = std::move(left), right = std::move(right)](typename T::resource_t& frame) {
        return right(left(frame));
    };
}

template <typename Pipe, Filter U>
auto addToPipe(Pipe&& left, U&& right)
{
    using input_t = typename function_traits<Pipe>::arg<0>::type;
    using pipe_return_t = typename function_traits<Pipe>::result_type;
    using middle_t = typename U::resource_t;

    static_assert(std::is_same_v<pipe_return_t, middle_t>);
}