小编kib*_*ibe的帖子

在 F# 中，您可以执行以下操作：

type DeliveredOrderData =
  {
    OrderId: int;
    DateDelivered: DateTime;
  }

type UndeliveredOrderData =
  {
    OrderId: int;
  }

type Order = 
  | Delivered of DeliveredOrderData
  | Undelivered of UndeliveredOrderData

然后我可以创建根据状态返回的函数：

let putOnTruck order = 
  match order with
    | Undelivered {OrderId=id} ->
      OutForDelivery {OrderId=id}
    | Delivered _ ->
      failwith "package already delivered"

我了解了如何在 TypeScript 中创建类型，但是我该如何做与上面相同的事情呢？

const putOrderOnTruck = (order: UndeliveredOrder) => {
  // how can I make sure order is really UndeliveredOrder?
}