either.scala

import scala.util.{Left, Right}


case class Name(value: String) extends AnyVal {
  def +(s: Name) = Name(this.value + s)

  override def toString: String = value
}

implicit def strToName(s: String) = Name(s)

def validateName(s: String): Either[String, Name] = {
  if (s.isEmpty) Left("Name cannot be empty")
  else Right(Name(s))
}


validateName("ss") match {
  case Left(reason) => println(s"Oops: $reason")
  case Right(name) => println(s"your name is ${name.value}")
}

for {
  f <- validateName("Alliot")
  l <- validateName("Alderson")
} yield f + " " + l

for {
  f <- validateName("Alliot")
  l <- validateName("")
} yield f + " " + l