What Automatic Resource Management alternatives exist for Scala?

Question

I have seen many examples of ARM (automatic resource management) on the web for Scala. It seems to be a rite-of-passage to write one, though most look pretty much like one a

Answer 1

Here is @chengpohi's answer, modified so it works with Scala 2.8+, instead of just Scala 2.13 (yes, it works with Scala 2.13 also):

def unfold[A, S](start: S)(op: S => Option[(A, S)]): List[A] =
  Iterator
    .iterate(op(start))(_.flatMap{ case (_, s) => op(s) })
    .map(_.map(_._1))
    .takeWhile(_.isDefined)
    .flatten
    .toList

def using[A <: AutoCloseable, B](resource: A)
                                (block: A => B): B =
  try block(resource) finally resource.close()

val lines: Seq[String] =
  using(new BufferedReader(new FileReader("file.txt"))) { reader =>
    unfold(())(_ => Option(reader.readLine()).map(_ -> ())).toList
  }