When we have a sequence of Futures, or a list of Futures, or a collection of Futures, we should use one of the Future combinator APIs, Future.sequence(), to deal with this scenario.
This Future.sequence() function converts a list of Futures into a single Future that means collections of Futures into a single Future.
In simple words, List[Future[T]] ======> Future[List[T]].
It is also known as composing Futures. The following diagram demonstrates how Scala Future's sequence() function converts List[Future[T]] into Future[List[T]]:
Consider the following example:
scala> val pricesList:List[Future[Int]] = List(Future(1001),Future(999),Future(-2000),Future(1000)) pricesList: List[scala.concurrent.Future[Int]] = List(scala.concurrent.impl.Promise$DefaultPromise@680a66dd, scala.concurrent.impl.Promise$DefaultPromise@2dd8239, scala.concurrent.impl...
