scala

问题 According to akka streams docs one can handle stream failure by defining a decider that maps a Throwable to a Strategy : val decider: Supervision.Decider = { case _: ArithmeticException => Supervision.Resume case _ => Supervision.Stop } I wonder if there is a way to also get access to the element that caused the error. Of course, the type of this element is unknown, but is there a way to get it even as an instance of Object ? 回答1: The trivial way would be to catch the ArithmeticException near

问题 According to akka streams docs one can handle stream failure by defining a decider that maps a Throwable to a Strategy : val decider: Supervision.Decider = { case _: ArithmeticException => Supervision.Resume case _ => Supervision.Stop } I wonder if there is a way to also get access to the element that caused the error. Of course, the type of this element is unknown, but is there a way to get it even as an instance of Object ? 回答1: The trivial way would be to catch the ArithmeticException near

问题 From the An Overview of the Scala Programming Language, Second Edition : // Scala object PrintOptions { def main(args: Array[String]): Unit = { System.out.println("Options selected:") for (val arg <- args) if (arg.startsWith("-")) System.out.println(" " + arg.substring(1)) } } In the example above, the Scala program invokes methods startsWith and substring of String , which is a class defined in Java. It also accesses the static out field of the Java class System , and invokes its (overloaded

问题 From the An Overview of the Scala Programming Language, Second Edition : // Scala object PrintOptions { def main(args: Array[String]): Unit = { System.out.println("Options selected:") for (val arg <- args) if (arg.startsWith("-")) System.out.println(" " + arg.substring(1)) } } In the example above, the Scala program invokes methods startsWith and substring of String , which is a class defined in Java. It also accesses the static out field of the Java class System , and invokes its (overloaded

问题 I am learning Scala and I was trying to create a type class to solve the "Every animal eats food, but the type of food depends on the animal" problem. I have an Eats type class with context bounds: trait Eats[A <: Animal, B <: Edible] object Eats { def apply[A, B]: Eats[A, B] = new Eats[A, B] {} } with both Animal and Edible being abstract classes. The (reduced) Animal interface looks something like this abstract class Animal { type This // concrete type def eat[A <: Edible](food: A)(implicit

问题 I am learning Scala and I was trying to create a type class to solve the "Every animal eats food, but the type of food depends on the animal" problem. I have an Eats type class with context bounds: trait Eats[A <: Animal, B <: Edible] object Eats { def apply[A, B]: Eats[A, B] = new Eats[A, B] {} } with both Animal and Edible being abstract classes. The (reduced) Animal interface looks something like this abstract class Animal { type This // concrete type def eat[A <: Edible](food: A)(implicit

问题 I have created a simple feeder in Gatling with CSV. The script is working well and not getting any errors. I know values are fetching from the CSV during the load test. But how can I ensure which value is getting for each user. I have to ensure that first user should login with UserName: user1 and Password: password1. As I am very very new to Gatling I could not find a solution for this. Hence please help me to get a solution , Thanks in advance...... My CSV contains- Username Password user1

问题 I have a DataSet.map operation that needs to pull data in from an external REST API. The REST API client returns a Future[Int] . Is it possible to have the DataSet.map operation somehow await this Future asynchronously? Or will I need to block the thread using Await.result ? Or is this just not the done thing... i.e. should I instead try and load the data held by the API into a DataSet of its own, and perform a join ? Thanks in advance! EDIT: Different from: Spark job with Async HTTP call

问题 The Scala compiler generates byte code like Java compiler which could be run on a platform dependent JVM right?Then why do we need complete JDK as a pre-requisite?Is it for including few Java items within scala and debugging it?Please provide some insights. 回答1: I've just tested this claim on a system with sbt and a JRE but no JDK. Compiling works fine: the JDK is not required. You'll need it for jarsigner if you are going to sign your .jar files or do other obscure things. 回答2: From the

问题 The Scala compiler generates byte code like Java compiler which could be run on a platform dependent JVM right?Then why do we need complete JDK as a pre-requisite?Is it for including few Java items within scala and debugging it?Please provide some insights. 回答1: I've just tested this claim on a system with sbt and a JRE but no JDK. Compiling works fine: the JDK is not required. You'll need it for jarsigner if you are going to sign your .jar files or do other obscure things. 回答2: From the