monoid_reverse.hpp

#pragma once

template <class Monoid>
struct Monoid_Reverse {
  using value_type = typename Monoid::value_type;
  using X = value_type;
  static constexpr X op(const X &x, const X &y) { return Monoid::op(y, x); }
  static constexpr X unit() { return Monoid::unit(); }
  static const bool commute = Monoid::commute;
};