What are scala futures

A Scala Future is used to create a temporary pocket of concurrency that you use for one-shot needs. You typically use it when you need to call an algorithm that runs an indeterminate amount of time — such as calling a web service or executing a long-running algorithm — so you therefore want to run it off of the main thread. Scala Futures While an Akka actor runs for a long time and is intended to handle many messages over its lifetime, a Scala Future is intended as a one-shot, “handle this relatively slow and potentially long-running computation, and call me back with a result when you’re done” construct. A Future gives you a simple way to run an algorithm concurrently. A future starts running concurrently when you create it and returns a result at some point, well, in the future. In Scala, it’s said that a future returns “eventually.” The following examples show a variety of ways to create futures and work with their eventual results. Back to top

26 Apr 2018 Scala Futures: Introduction; Method with future as return type; Non blocking future result; Chain futures using flatMap; Chain futures using for  pipeTo only listens to a Future to send its value to an actor. Same story in Akka Streams: mapAsync only accepts Futures. Play Framework — based on Akka —  The amazing world of Asynchronous Programming made SIMPLE with Scala. Why? Multi-threading is the future. Computers are getting diminishing returns on   A Scala Future is used to create a little pocket of concurrency that you use for one -shot needs. You typically use it when you need to call an algorithm that runs  17 Dec 2019 Future import scala.concurrent.ExecutionContext.Implicits.global object Addition extends App { val firstNum = 5 val secondNum = 6 val addition  24 Nov 2018 As in many other languages, Scala Future is a placeholder representing a value that will be computed soon. It's immutable - once computed it  In your example you can consider equivalent p success { 10 } and Future(10) . You will only need to extract the future from p to get the same result. You may 

18 Dec 2013 During job interviews we often give Scala developers a simple design task: to model a binary tree. The simplest but not necessarily best 

This page provides an introduction to Futures in Scala, including Future callback methods. 16 Jan 2020 A Future gives you a simple way to run an algorithm concurrently. A future starts running concurrently when you create it and returns a result at  18 Apr 2017 Futures are the standard mechanism for writing multithreaded code in Scala. Whenever we create a new Future operation, Scala spawns a new  26 Apr 2018 Scala Futures: Introduction; Method with future as return type; Non blocking future result; Chain futures using flatMap; Chain futures using for  pipeTo only listens to a Future to send its value to an actor. Same story in Akka Streams: mapAsync only accepts Futures. Play Framework — based on Akka — 

By default, futures and promises are non-blocking, making use of callbacks instead of typical blocking operations. To simplify the use of callbacks both syntactically and conceptually, Scala provides combinators such as flatMap, foreach, and filter used to compose futures in a non-blocking way.

21 Jun 2018 Handling Rate-Limits with Scala Futures. Slow down while going fast to go faster. Get Practical Scala for Java Developers now with O'Reilly online learning. O' Reilly members experience live online training, plus books, videos, and digital  7 Oct 2014 _ import scala.concurrent.ExecutionContext.Implicits.global //note the type declaration, Future[User] def getUserFromUsername(name: String):  5 Jun 2016 The concepts Promise and a Future go hand in hand. A scala.concurrent.Promise is the one which sets a value for the Future . In other words 

16 Jan 2020 A Future gives you a simple way to run an algorithm concurrently. A future starts running concurrently when you create it and returns a result at 

This is the documentation for the Scala standard library. Package structure . The scala package contains core types like Int, Float, Array or Option which are accessible in all Scala compilation units without explicit qualification or imports.. Notable packages include: scala.collection and its sub-packages contain Scala's collections framework. scala.collection.immutable - Immutable

How to resolve a list of futures in Scala - Stack Overflow stackoverflow.com/questions/20012364/how-to-resolve-a-list-of-futures-in-scala

import scala.concurrent.duration.Duration class UserRepos0(implicit ec: ExecutionContext) extends UserRepos[Future] { override val F = implicitly[Monad[ Future]] I wonder what was the motivation for designing future the way it is right now in Scala? What absolutely drives me mad is that anytime you do a map/flatMap, you   15 Jul 2016 Scala's futures are quite nice to use in comparison to similar devices in many other languages: we can put code in a Future , where it will run  In computer science, future, promise, delay, and deferred refer to constructs used for FutureKit, implements a version for Apple GCD; FutureLib, pure Swift 2 library implementing Scala-style futures and promises with TPL-style cancellation   15 Oct 2015 Quite often you have to deal with many futures at once. In such cases for comprehension comes handy,and because scala's Future is actually a  18 Dec 2013 During job interviews we often give Scala developers a simple design task: to model a binary tree. The simplest but not necessarily best  This is the second of several posts describing protips for scala.concurrent.Future. For the previous post, click here.

This is the documentation for the Scala standard library. Package structure . The scala package contains core types like Int, Float, Array or Option which are accessible in all Scala compilation units without explicit qualification or imports.. Notable packages include: scala.collection and its sub-packages contain Scala's collections framework. scala.collection.immutable - Immutable .sequence was a bit hard to follow in the source of scala.concurrent.Future, I wonder how I would implement a parallel that waits for all original futures of a (dynamically sized) sequence, or what might be the problem here. Suppose I have several futures and need to wait until either any of them fails or all of them succeed.. For example: Let there are 3 futures: f1, f2, f3. If f1 succeeds and f2 fails I do not wait for f3 (and return failure to the client).. If f2 fails while f1 and f3 are still running I do not wait for them (and return failure) . If f1 succeeds and then f2 succeeds I continue waiting for f3.