Question

Say I have some code:

def foo(s:String):Either[Bar, Baz] = // some code here ... 

I want to use it as:

val a = Array("a", "b", "c")
a.map(foo) match {
   case something => // should match when all elements in array are of type Right
   case _ =>
}

Can anyone suggest code for “something”

EDIT: Prefer to match and use array of Right[Bar,Baz] directly rather than having to extract after match.

Answer 1

Use the forall method to check that all elements in the array are isRight:

a.map(foo) match {
  case eithers if eithers.forall(_.isRight) =>
  case _ =>
}

Regarding your comment, if you want the match and convert-to-right all in one pass, then try a custom extractor:

object RightArrayExtractor {
  def unapply(eithers: Array[Either[Bar, Baz]]) =
    eithers.foldLeft(Option(Vector[Right[Bar, Baz]]())) {
      case (Some(z), x @ Right(_)) => Some(z :+ x)
      case (None, _) => None
      case (_, Left(x)) => None
    }
}

a.map(foo) match {
  case RightArrayExtractor(eithers) => // eithers is a Vector[Right[Bar,Baz]]
  case _ =>
}