A way to build Eithers as Left or Right specifying the other side's type but with type inference for the value

Eithers.scala

package scala.util

class RightBuilder[+L] private[util]() { def apply[R](r: R): Right[L, R] = Right(r) }
class LeftBuilder[+R] private[util]() { def apply[L](l: L): Left[L, R] = Left(l) }

object Eithers {

  private val leftBuilder = new LeftBuilder[Nothing]
  private val rightBuilder = new RightBuilder[Nothing]

  def left[R]: LeftBuilder[R] = leftBuilder
  def right[L]: RightBuilder[L] = rightBuilder
}

import scala.util.Eithers._

object Main {
  def main(args: Array[String]): Unit = {
    val x = right[String](5)
    val y = right[Int]("hi")
    val x1 = left[Int]("hi")
    val y1 = left[String](5)
  }
}