Scala for the Impatient. 2nd Ed

 The evolution of traditional languages such as Java, C#, and C++ has slowed down considerably, and programmers who are eager to use more modern language features are looking elsewhere. Scala is an attractive choice; in fact, I think it is by far the most attractive choice for programmers who want to improve their productivity. Scala has a concise syntax that is refreshing after the Java boilerplate. It runs on the Java virtual machine, providing access to a huge set of libraries and tools. And Scala doesn’t just target the Java virtual machine. The ScalaJS project emits JavaScript code, enabling you to write both the server-side and client-side parts of a web application in a language that isn’t JavaScript. Scala embraces the functional programming style without abandoning object orientation, giving you an incremental learning path to a new paradigm. The Scala interpreter lets you run quick experiments, which makes learning Scala very enjoyable. Last but not least, Scala is statically typed, enabling the compiler to find errors, so that you don’t waste time finding them—or not—later in the running program.

 I wrote this book for impatient readers who want to start programming in Scala right away. I assume you know Java, C#, or C++, and I don’t bore you with explaining variables, loops, or classes. I don’t exhaustively list all the features of the language, I don’t lecture you about the superiority of one paradigm over another, and I don’t make you suffer through long and contrived examples. Instead, you will get the information that you need in compact chunks that you can read and review as needed. Scala is a big language, but you can use it effectively without knowing all of its details intimately. Martin Odersky, the creator of Scala, has identified levels of expertise for application programmers and library designers—as shown in the following table.