Named Operators in C++ and Unicode

main.cpp

// Testedt with GCC and CLang
// Not working with ICC due to the UTF-8
// MSVC requires /utf-8 option
#include <iostream>

// from https://riptutorial.com/cplusplus/example/23817/named-operators
// modified to use < > instead of *
// modified for adding unary version
namespace named_operator {
  template<class D>struct make_operator{constexpr make_operator(){}};

  template<class T, char, class O> struct half_apply { T&& lhs; };

  template<class Lhs, class Op>
  half_apply<Lhs, '<', Op> operator<( Lhs&& lhs, make_operator<Op> ) {
    return {std::forward<Lhs>(lhs)};
  }

  template<class Lhs, class Op, class Rhs>
  auto operator>( half_apply<Lhs, '<', Op>&& lhs, Rhs&& rhs )
  -> decltype( named_invoke( std::forward<Lhs>(lhs.lhs), Op{}, std::forward<Rhs>(rhs) ) )
  {
    return named_invoke( std::forward<Lhs>(lhs.lhs), Op{}, std::forward<Rhs>(rhs) );
  }

    template<class Op, class Rhs>
  auto operator>( make_operator<Op> , Rhs&& rhs )
  -> decltype( named_invokeL( Op{}, std::forward<Rhs>(rhs) ) )
  {
    return named_invokeL( Op{}, std::forward<Rhs>(rhs) );
  }

}

// example 
namespace my_ns {
  struct range_t : named_operator::make_operator<range_t> {};
  constexpr range_t α{};
  
  std::pair<int, int> named_invoke( int a, range_t, int b ) {
      return std::pair<int, int>(a,b);
  }
}

namespace my_sq3 {
  struct sqrt3_t : named_operator::make_operator<sqrt3_t> {};
  constexpr sqrt3_t sq3{};
  
  double named_invokeL( sqrt3_t, int b ) {
      return -b;
  }

}
using my_ns::α;
using my_sq3::sq3;

int main()
{
    auto r =  (2 <α> 3);
    auto w = sq3> 3;
    std::cout << "r = " << r.first << " " << r.second << std::endl;
    std::cout << "w = " << w << std::endl;
    return 0;
}