I have learned the basic difference between foldLeft and reduceLeft foldLeft: initial value has to be passed reduceLeft: takes first element of the collection as initial value throws exception if collection is empty Is there any other difference ? Any specific reason to have two methods with similar functionality? 8 Answers 8
Closed. This question is opinion-based. It is not currently accepting answers. Want to improve this question? Update the question so it can be answered with facts and citations by editing this post. Closed 8 years ago. Improve this question Recently scalaz caught my eye. It looks very interesting, but I have not found any good … Read more
I have the following piece of code from this question: def addChild(n: Node, newChild: Node) = n match { case Elem(prefix, label, attribs, scope, child @ _*) => Elem(prefix, label, attribs, scope, child ++ newChild : _*) case _ => error(“Can only add children to elements!”) } Everything in it is pretty clear, except this … Read more
Newbie question of Akka – I’m reading over Akka Essentials, could someone please explain the difference between Akka Stop/Poison Pill vs. Kill ? The book offers just a small explaination “Kill is synchronous vs. Poison pill is asynchronous.” But in what way? Does the calling actor thread lock during this time? Are the children actors … Read more
Closed. This question needs to be more focused. It is not currently accepting answers. Want to improve this question? Update the question so it focuses on one problem only by editing this post. Closed 6 years ago. Improve this question The Akka Streams library already comes with quite a wealth of documentation. However, the main … Read more
In Scala 2.8, there is an object in scala.collection.package.scala: def breakOut[From, T, To](implicit b : CanBuildFrom[Nothing, T, To]) = new CanBuildFrom[From, T, To] { def apply(from: From) = b.apply() ; def apply() = b.apply() } I have been told that this results in: > import scala.collection.breakOut > val map : Map[Int,String] = List(“London”, “Paris”).map(x => … Read more
Let’s say I have a case class that represents personas, people on different social networks. Instances of that class are fully immutable, and are held in immutable collections, to be eventually modified by an Akka actor. Now, I have a case class with many fields, and I receive a message that says I must update … Read more
How in the world do you get just an element at index i from the List in scala? I tried get(i), and [i] – nothing works. Googling only returns how to “find” an element in the list. But I already know the index of the element! Here is the code that does not compile: def … Read more
What is the difference between: def even: Int => Boolean = _ % 2 == 0 and val even: Int => Boolean = _ % 2 == 0 Both can be called like even(10). 9 Answers 9
Is there any difference between case object and object in scala? 7 Answers 7
