scala - 是否有与 Haskell 的 Data.This (A, B, or (A and B)) 等效的 Scala？

Question

Haskell 摘要 these包裹:

The 'These' type represents values with two non-exclusive possibilities

data These a b = This a | That b | These a b

Scala 中有类似的东西吗？也许在scalaz？

对于那些不熟悉 Haskell 的人，这里有一个粗略的草图，说明如何在 Scala 中解决这个问题:

sealed trait These[+A, +B] {
  def thisOption: Option[A]
  def thatOption: Option[B]
}

trait ThisLike[+A] {
  def `this`: A
  def thisOption = Some(a)
}

trait ThatLike[+B] {
  def `that`: B
  def thatOption = Some(b)
}

case class This[+A](`this`: A) extends These[A, Nothing] with ThisLike[A] {
  def thatOption = None
}

case class That[+B](`that`: B) extends These[Nothing, B] with ThatLike[B] {
  def thisOption = None
}

case class Both[+A, +B](`this`: A, `that`: B) extends These[A, B]
  with ThisLike[A] with ThatLike[B]

或者你可以做一些类似组合 Either 的事情。 s:

type These[A, B] = Either[Either[A, B], (A, B)]

(显然，表达数据结构并不困难。但如果​​库中现有的东西已经经过深思熟虑，我宁愿使用它。)

Answer 1

scalaz 有这些，也称为 \&/
https://github.com/scalaz/scalaz/blob/series/7.2.x/core/src/main/scala/scalaz/These.scala