Either to Try and vice versa in Scala

Question

Are there any conversions from Either to Try and vice versa in the Scala standard library ? Maybe I am missing something but I did not find them.

Answer 1

To the best of my knowledge this does not exist in the standard library. Although an Either is typically used with the Left being a failure and the Right being a success, it was really designed to support the concept of two possible return types with one not necessarily being a failure case. I'm guessing these conversions that one would expect to exist do not exist because Either was not really designed to be a Success/Fail monad like Try is. Having said that it would be pretty easy to enrich Either yourself and add these conversions. That could look something like this:

object MyExtensions {   implicit class RichEither[L <: Throwable,R](e:Either[L,R]){     def toTry:Try[R] = e.fold(Failure(_), Success(_))   }    implicit class RichTry[T](t:Try[T]){     def toEither:Either[Throwable,T] = t.transform(s => Success(Right(s)), f => Success(Left(f))).get   }   }  object ExtensionsExample extends App{   import MyExtensions._    val t:Try[String] = Success("foo")   println(t.toEither)   val t2:Try[String] = Failure(new RuntimeException("bar"))   println(t2.toEither)    val e:Either[Throwable,String] = Right("foo")   println(e.toTry)   val e2:Either[Throwable,String] = Left(new RuntimeException("bar"))   println(e2.toTry) }