Either in 2.13 - What's the replacement for 'right'?

Question
1

Before 2.13 we could access the right value of an Either as Either.right, which is now deprecated.

What’s the replacement for this statement?

2

You can use pattern-matching in the Either values:

either match{
case Rigth(a) => doSomething(a)
case Left(b) => doSomething(b)
}

EDIT
This is the link to the scala doc https://www.scala-lang.org/api/current/scala/util/Either.html

3

You could also use getOrElse, which is often more convenient than right.

1 Like
4

It depends what you want to do next.

If you want to map or flatMap, you can just omit it because they exist on Either now and are right-biased.

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5

I just want the plain value to compare it in an unit test.

In the productive code I’d know how to deal with Either.

6

Compare to Right(x) or pattern match and compare inside the Right branch.

2 Likes
7

If explicit Right comparison or pattern matching isn’t your thing, you could resort to using myEither.toOption.get - which will produce a “None.get” exception if myEither is a Left.

If you’re using scalatest, you can consider using cats.scalatest.EitherValues (instead of org.scalatest.EitherValues, which will produce deprecation warnings on 2.13), which will allow syntax like

myEither.value must be (foo)

and, when myEither is a Left, will produce an error message detailing what was contained in that unexpected Left.

1 Like
8

You could also use a pattern, e.g.

val Right(foo) = either
foo shouldBe bar
9

In Specs2 you can use beRight (and beLeft)

  val right3 = Right(3)
  val leftError = Left("error")

  right3 must beRight
  leftError must beLeft
  
  right3 must beRight(3)
  leftError must beLeft("error")

https://etorreborre.github.io/specs2/guide/SPECS2-2.4.17/org.specs2.guide.Matchers.html

1 Like