Learning Concurrent Programming in Scala - Second Edition

The "Hello World" program

In this section, we go through a simple, working Hello World program. We will not go into too much, yet we will provide deeper information in the subsequent sections. For now, we will just define a reactor that waits for one incoming event, prints a message to the standard output once this event arrives, and then terminate.

We start by importing the contents of the io.reactors package:

import io.reactors._ 

This allows us to use the facilities provided by the Reactors framework. In the following snippet, we declare a simple reactor-based program:

 object ReactorHelloWorld { def main(args: Array[String]): Unit = { val welcomeReactor = Reactor[String] { self => self.main.events onEvent { name => println(s"Welcome, $name!") ...