auto GetStringPtrs(Runtime::Object* lhs, Runtime::Object* rhs) {
  using namespace Runtime;
  return pair(dynamic_cast<String*>(lhs), dynamic_cast<String*>(rhs));
}

auto GetNumberPtrs(Runtime::Object* lhs, Runtime::Object* rhs) {
  using namespace Runtime;
  return pair(dynamic_cast<Number*>(lhs), dynamic_cast<Number*>(rhs));
}

auto GetBoolPtrs(Runtime::Object* lhs, Runtime::Object* rhs) {
  using namespace Runtime;
  return pair(dynamic_cast<Bool*>(lhs), dynamic_cast<Bool*>(rhs));
}

template <typename BinOp>
ObjectHolder ArithOpOrError(Runtime::Object* lhs, Runtime::Object* rhs,
                            BinOp op) {
  using namespace Runtime;
  auto [str1, str2] = GetStringPtrs(lhs, rhs);
  if (str1 && str2)
    return ObjectHolder::Own(String(op(str1->GetValue(), str2->GetValue())));
  auto [num1, num2] = GetNumberPtrs(lhs, rhs);
  if (num1 && num2)
    return ObjectHolder::Own(Number(op(num1->GetValue(), num2->GetValue())));
  auto [bool1, bool2] = GetBoolPtrs(lhs, rhs);
  if (bool1 && bool2)
    return ObjectHolder::Own(Bool(op(bool1->GetValue(), bool2->GetValue())));
  throw runtime_error("not the same type or not ValueObject");
}