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Scala Dotty 联合类型 DaysOfTheWeek 示例

转载 作者:行者123 更新时间:2023-12-04 03:13:33 27 4
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Scala Dotty 官方团队展示了来自 ( https://d-d.me/talks/scalaworld2015/#/12 ) 的这个例子

object DaysOfTheWeek {
object Mon
object Tue
object Wed
object Thu
object Fri
object Sat
object Sun

type Weekend = Sat.type | Sun.type
type Workweek = Mon.type | Tue.type | Wed.type | Thu.type | Fri.type
type All = Weekend | Workweek
}

如果我使用最新的 Dotty nightly build,截至本文发布时为“0.1.1-20170322-5fd7a95-NIGHTLY”,该示例会导致以下错误:

Error:(13, 18) Singleton type DaysOfTheWeek.Sat.type is not allowed in a union type
Error:(13, 29) Singleton type DaysOfTheWeek.Sun.type is not allowed in a union type
Error:(14, 19) Singleton type DaysOfTheWeek.Mon.type is not allowed in a union type
Error:(14, 30) Singleton type DaysOfTheWeek.Tue.type is not allowed in a union type
Error:(14, 41) Singleton type DaysOfTheWeek.Wed.type is not allowed in a union type
Error:(14, 52) Singleton type DaysOfTheWeek.Thu.type is not allowed in a union type
Error:(14, 63) Singleton type DaysOfTheWeek.Fri.type is not allowed in a union type

有什么办法可以使这个官方示例正常工作吗?

最佳答案

这现在有效:

enum DaysOfTheWeek {
case Mon
case Tue
case Wed
case Thu
case Fri
case Sat
case Sun
type Weekend = Sat.type | Sun.type
type Workweek = Mon.type | Tue.type | Wed.type | Thu.type | Fri.type
type All = Weekend | Workweek
}

链接到 Scastie

关于Scala Dotty 联合类型 DaysOfTheWeek 示例,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/43004353/

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