C++ UFCS operator@

main.cpp

template <class Range>
Range firstHalf(const Range& r){
  auto&& begin = std::begin(r);
  auto&& begin_ = begin;
  
  return make<Range>(
    begin,
    std::next(
      begin_,
      std::distance(begin, std::end(r))
    )
  );
}

int main(){
  std::vector<int> v = {0,1,2,3,4,5,6};
  assert(firstHalf(v) == v@firstHalf());
}