gistfile1.txt

#include <array>
#include <functional>

template <typename T, size_t N, size_t M, size_t... iota_N, size_t... iota_M>
auto append_impl(
    std::index_sequence<iota_N...>, 
    std::index_sequence<iota_M...>,  
    const std::array<T, N>& a, 
    const std::array<T, M>& b
) -> std::array<T, N+M> {
    return { a[iota_N]..., b[iota_M]... };
}

template <typename T, size_t N, size_t M>
auto append(const std::array<T, N>& a, const std::array<T, M>& b) -> std::array<T, N+M> {
    return append_impl(std::make_index_sequence<N>{}, std::make_index_sequence<M>{}, a, b);
}

#include <cstdlib>
#include <cstdio>

int main(int argc, char** argv) {
	std::array<int, 1> a {1};
	std::array<int, 2> b {2, 3};
	auto c = append(a, b);
	for (auto v : c) {
		printf("%i\n", v);
	}
}