This is an excerpt from my book, Hello, Scala. In this lesson I’ll show two examples of applications that use Akka actors, both of which can help you get started with my larger “Alexa written with Akka” = Aleka application.Back to top
An Akka “Hello, world” example
First, let’s look at an example of how to write a “Hello, world” application using Akka.
Writing a “Hello” actor
An actor is an instance of the
akka.actor.Actor class, and once it’s created it starts running on a parallel thread, and all it does is respond to messages that are sent to it. For this “Hello, world” example I want an actor that responds to “hello” messages, so I start with code like this:
In this final, third part of my three-part introductory series on Scala.js I’ll demonstrate a technique that can help you build single-page web applications with Scala.js. That is, the body of your HTML page will look like this:
In my first “Hello, world” Scala.js tutorial I showed how to get started with Scala.js, including some necessary setup/configuration work. That tutorial ended by showing how to get the string “Hello, world” displayed in a browser.
This is the first tutorial in a three-part series on getting started with Scala.js. This tutorial will demonstrate the proverbial “Hello, world” introduction. After this “Hello, world” tutorial, the next two tutorials will show some more powerful things you can do with Scala.js.
As I try to organize things a bit around here, here’s a list of some tutorials I’ve written lately about the Scala collections classes:
Way back when I lived in this low-income apartment complex in Wasilla, Alaska — technically I had no income at the time, and it’s ridiculously hard to find a place to live in Alaska in the summer — and spent as much time as I could meditating in the mountains, I created a vi/vim editor video tutorial and put it on YouTube. I just noticed that video has now exceeded 200,000 views. It feels a little weird to think that over 200K people have started to learn vi/vim from that video.
A funny thing about making that video is that the walls in that apartment complex were paper-thin. I could hear everything my neighbors did in their apartments (use your imagination and you won’t be wrong), and they could hear me, so I intentionally tried not to talk too loud in the video. I had to edit the video at several points to crop out some of my neighbors yelling at each other.
I wrote the Scala Cookbook for programmers looking for solutions to common Scala problems, and then wrote Functional Programming, Simplified for programmers looking for a simple way to learn functional programming. A few months ago I decided to finish my Scala trilogy and write a book for programmers who don’t know Scala and want a quick introduction to it. With that, Hello, Scala was born:
The Andreessen Horowitz website has a blog post titled The Crypto Canon which has links to good resources on what a blockchain is, how bitcoin and others work, Ethereum, and much more.
Here’s a link to an H2 JDBC database tutorial (just some sample code).