Function read_array

mergesort.cpp:8–19

using Num = long long int;

static constexpr auto read_array(auto array, auto len) noexcept {
  return block_(
    array[0] = io::read<Num>(),
    if_(array[0] == none_)(
      len = 0
    )->else_(
      for_(len = 1, io::read<char>() == ',', ++len)(
        array[*len] = io::read<Num>()
      )
    )
  );
}

static constexpr auto write_array(auto array, auto len) noexcept {
  constexpr struct : local {} stack;