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Transform from List[Future[...] to List[...] in Scala

Is there a method (or simple way) in scala that helps to transform List[Future[...]] to List[...]?

If such a method is in the Seq, then it is also suitable. I spent a lot of time looking, but I couldn't find anything. Thanks

Solution

  • sequence can turn List[Future[A]] to Future[List[A]] and then you could await the future

    val fxs: Future[List[Int]] = Future.sequence(List(Future(1), Future(2)))
val xs: List[Int] = Await.result(fxs, Duration.Inf)
// work with xs

    however usually it is preferable to map over the future instead of awaiting like so

    fxs.map { xs: List[Int] =>
  // work with xs
}