RNG recipe

rng.hpp

#include <algorithm>
#include <array>
#include <functional>
#include <iterator>
#include <random>

template <typename Generator = std::mt19937>
[[nodiscard]] auto get_rng() -> auto & {
  thread_local auto rng = [] {
    auto seed_data = std::array<int, Generator::state_size>{};
    auto r = std::random_device{};
    std::ranges::generate(seed_data, std::ref(r));
    auto seq = std::seed_seq{std::begin(seed_data), std::end(seed_data)};
    return Generator{seq};
  }();
  return rng;
}