How to split a List[Either[A, B]]

Question

I want to split a List[Either[A, B]] in two lists.

Is there a better way ?

def lefts[A, B](eithers : List[Either[A, B]]) : List[A] = eit         


        

Answer 1

A somewhat functional solution for Seq.

def partition[A, B](seq: Seq[Either[A, B]]): (Seq[A], Seq[B]) = {
  seq.foldLeft[(Seq[A], Seq[B])]((Nil, Nil)) { case ((ls, rs), next) =>
    next match {
      case Left(l) => (ls :+ l, rs)
      case Right(r) => (ls, rs :+ r)
    }
  }
}