Print range in C++

print-range.cpp

#include <iostream> // cout
#include <ranges>   // range, subrange, cbegin, cend
#include <vector>

namespace {

auto print_range(const std::ranges::range auto &range, bool newline = true)
    -> void;

namespace detail {

auto
print(const std::ranges::range auto &value) -> void {
  print_range(value, false);
}

auto
print(const auto &value) -> void {
  std::cout << value;
}

} // namespace detail

auto
print_range(const std::ranges::range auto &range, bool newline) -> void {
  const auto begin = std::ranges::cbegin(range);
  const auto end = std::ranges::cend(range);

  std::cout << '[';

  for (auto &&i : std::ranges::subrange(begin, end - 1)) {
    // std::cout << i << ",";
    detail::print(i);
    std::cout << ',';
  }

  // std::cout << *(end - 1) << ']';
  detail::print(*(end - 1));
  std::cout << ']';

  if (newline)
    std::cout << '\n';
}

} // namespace

auto
main() -> int {
  std::vector<std::vector<int>> v{{1, 2, 3}, {2, 4, 6}, {3, 6, 9}};
  // [[1,2,3],[2,4,6],[3,6,9]]
  print_range(v);
}