Scala tail recursion from finally block

Question

I want to apply a function f to each element of a List and not stop at the first error but throw the last error (if any) only:

@annotation.tailrec
def tryAll[A](xs: List[A])(f: A => Unit): Unit = {
  xs match {
    case x :: xt =>
      try {
        f(x)
      } finally {
        tryAll(xt)(f)
      }
    case _ =>
  }
}

But, the above code does not compile - it is complaining that this function is not tail recursive. Why not?

Answer 1

This solution iterates over all elements and produces (throws) the last error if any:

def tryAll[A](xs: List[A])(f: A => Unit): Unit = {
  val res = xs.foldLeft(Option.empty[Throwable]) {
    case (maybeThrowable, a) =>
      Try(f(a)) match {
        case Success(_) => maybeThrowable
        case Failure(e) => Option(e)
      }
  }

  res.foreach(throwable => throw throwable)
}