Question

F＃中的类型声明示例：

type ActiveCartData = { UnpaidItems: string list }
type PaidCartData = { PaidItems: string list; Payment: float }

type ShoppingCart = 
    | EmptyCart  // no data
    | ActiveCart of ActiveCartData
    | PaidCart of PaidCartData

我们如何使用trait和case class和/或case object在Scala中执行类似操作？

一个开始：

trait ShoppingCart
case object EmptyCart extends ShoppingCart
case object ActiveCart extends ShoppingCart
case object PaidCart extends ShoppingCart

但是如何与数据持有者类型建立关系？

Answer 1

如果我理解正确，您正在寻找case classes而不是case objects。他们可以包装数据：

sealed trait ShoppingCart
case object EmptyCart extends ShoppingCart
case class ActiveCart(unpaidItems: Seq[String]) extends ShoppingCart
case class PaidCart(paidItems: Seq[String], payment: Float) extends ShoppingCart

或（如果你想保留这些持有者数据类型，除非它们非常复杂，否则我可能不会这样做）

sealed trait ShoppingCart
case object EmptyCart extends ShoppingCart
case class ActiveCart(unpaidItems: ActiveCartData) extends ShoppingCart
case class PaidCart(paidItems: PaidCartData) extends ShoppingCart

Scala是否具有F＃的“类型”？

1 个答案: