混合數值型別的算術運算子錯誤

無法新增整數和真實 *

- 5 + 1.0;
stdIn:1.2-10.4 Error: operator and operand don't agree [overload conflict]
  operator domain: [+ ty] * [+ ty]
  operand:         [+ ty] * real
  in expression:
    5 + 1.0