enum Money {
  WON,
  DOLLAR,
}

interface Won {
  type: Money.WON,
}
interface Dollar {
  type: Money.DOLLAR,
}

function moneyOrDollar(param: Won | Dollar) {
  if (param.type === Money.WON) {
    param;
  } else {
    param;
  }
}
// (parameter) param: Won
// (parameter) param: Dollar