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# Untitled

a guest Oct 12th, 2017 42 Never
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1. def lefts[A, B](eithers : List[Either[A, B]]) : List[A] = eithers.collect { case Left(l) => l}
2. def rights[A, B](eithers : List[Either[A, B]]) : List[B] = eithers.collect { case Right(r) => r}
3.
4. scala> def splitEitherList[A,B](el: List[Either[A,B]]) = {
5.          val (lefts, rights) = el.partition(_.isLeft)
6.          (lefts.map(_.left.get), rights.map(_.right.get))
7.        }
8. splitEitherList: [A, B](el: List[Either[A,B]])(List[A], List[B])
9.
10. scala> val el : List[Either[Int, String]] = List(Left(1), Right("Success"), Left(42))
11. el: List[Either[Int,String]] = List(Left(1), Right(Success), Left(42))
12.
13. scala> val (leftValues, rightValues) = splitEitherList(el)
14. leftValues: List[Int] = List(1, 42)
15. rightValues: List[String] = List("Success")
16.
17. val (lefts, rights) = eithers.foldRight((List[Int](), List[String]()))((e, p) => e.fold(l => (l :: p._1, p._2), r => (p._1, r :: p._2)))
18.
19. import scalaz.std.list._
20. import scalaz.std.either._
22.
23. val el : List[Either[Int, String]] = List(Left(1), Right("Success"), Left(42))
24.
25. scala> val (lefts, rights) = el.separate
26. lefts: List[Int] = List(1, 42)
27. rights: List[String] = List(Success)
28.
29. val lefts = list.flatMap(_.left.toOption)
30. val rights = list.flatMap(_.right.toOption)
31.
32. def split[A,B](eithers : List[Either[A, B]]):(List[A],List[B]) = {
33.   val lefts = scala.collection.mutable.ListBuffer[A]()
34.   val rights = scala.collection.mutable.ListBuffer[B]()
35.   eithers.map {
36.     case Left(l) => lefts += l
37.     case Right(r) => rights += r
38.   }
39.   (lefts.toList, rights.toList)
40. }
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