ScalaでTryとOption

repl

scala> delete("hoge")
res3: scala.util.Try[Unit] = Success(())

scala> delete("fuga")
res4: scala.util.Try[Unit] = Failure(java.lang.IllegalArgumentException: cannot delete)

scala> delete("piyo")
res5: scala.util.Try[Unit] = Failure(java.util.NoSuchElementException: Predicate does not hold for None)

scala> delete("etc")
res6: scala.util.Try[Unit] = Failure(java.lang.IllegalArgumentException: cannot get)

scala> deleteWithMatch("hoge")
res7: scala.util.Try[Unit] = Success(())

scala> deleteWithMatch("fuga")
res8: scala.util.Try[Unit] = Failure(java.lang.IllegalArgumentException: cannot delete)

scala> deleteWithMatch("piyo")
res9: scala.util.Try[Unit] = Failure(java.lang.IllegalArgumentException: not found)

scala> deleteWithMatch("etc")
res10: scala.util.Try[Unit] = Failure(java.lang.IllegalArgumentException: cannot get)

TryOption.scala

import scala.util.Try
case class Data(aId: String)

def get(aId: String): Try[Option[Data]] = Try{ aId match {
  case "hoge" | "fuga" => Some(Data(aId))
  case "piyo" => None
  case _ => throw new IllegalArgumentException("cannot get")
}}


def deleteData(aData: Data): Try[Unit] = Try{ aData match {
  case Data("hoge") => ()
  case _ => throw new IllegalArgumentException("cannot delete")
}}


def delete(aId: String): Try[Unit] = {
  for{
    Some(tData) <- get(aId)
    _ <- deleteData(tData)
  } yield ()
}

def deleteWithMatch(aId: String): Try[Unit] = {
  get(aId) map {
    case Some(tData) => tData
    case None => throw new IllegalArgumentException("not found")
  } flatMap (deleteData)
}