Programming Scala: Scalability = Functional Programming + Objects (Animal Guide)

Original review written by Roberto Bentivoglio, JUG Lugano www.juglugano.ch Scala is a recent programming language that mixes the object-oriented programming with the functional programming and DSLs (Domain-Specific Languages). Programming Scala is a book written by Dean Wampler, consultant, trainer and mentor with Object Mentor, Inc. He specializes in Scala, Java and Ruby. The second author is Alex Payne. He has been working since the beginning of 2007 for the Twitter, Inc. as Platform Lead. Knowing that Scala is the platform used to develop Twitter, one of the most worldwide used social network, the book becomes very promising. The first thing to know before studying this language is that it needs a relatively long time to be deeply understood. Scala presents some difference that, at the begin, can be heavy to digest to Java developer. Scala is introduced in the first chapter as a language that addresses the major needs of the modern developer. To explain the power of Scala the authors compare it with the most popular programming languages: Java, C#, Ruby, Python, PHP, etc. After a fast explanation on how to install the Scala environment the authors show the usual Hello World program code. In the subsequent chapters are explained all the concepts at the base of the Scala programming language: its syntax, the traits, its object-oriented and functional programming, the concurrency with the actors, DSLs, the Type system and a very interesting chapter about the application design with Scala. The last chapter covers the tools, the libraries and the IDE support for Scala. The book contains many (working) examples that are very useful to learn the Scala structure. The language used by the authors is not complicated and helps to easily understand theirs explanations. One of the major hallmarks of the book is that the authors try to use the Scala syntax that they consider the best from the first examples. This feature of the book can help to learn from the begin what they think is the best way to programming in Scala. On the other hand, for newbies it can turn out to be difficult to understand why it's better to use some structure or some syntax instead of others. Despite this feature, the final consideration is that "Programming Scala" is a good work and it's one of the best ways and one of the best books to enter in the wonderful Scala world. The first few chapters are breathtakingly fast. Some of the middle chapters are kind of slow, but are still worthwhile. Scala is a fairly large language (unlike, say, Scheme or C), and the book is a fairly dense 400 pages. I found it helpful to read slowly and take notes. As for Scala itself, I really like it! Scala is a nice mix of Java, C#, Erlang, Haskell, Ruby, and Smalltalk. You can treat it as a "better Java", or you can treat it as a more enterprise-friendly Haskell. Either way, it's exactly what I was looking for: a language with reasonable syntax, an ML type system, and a decent set of real world libraries. I know that the Haskell community is working hard in this direction as well. I think Scala stands a very good chance at being a work-friendly, programmer-friendly language. I'm a little afraid that its type system may be too large and too complex for a lot of programmers. To be fair, I think that C++ is too large and complex for most programmers too. I'm also afraid of subsetting--i.e. the situation where every team picks a different subset of the language to use. This is very common in multiparadigmatic languages like C++. On the other hand, some multiparadigmatic languages like Python seem to avoid this problem. Nonetheless, there's a lot to learn in Scala--covariance, contravariance, parameterized types, abstract types, self-type declarations, lazy values, by-name parameters, DSL-friendly abbreviations, path dependent types, oh my! And there's more! I ended up with 50 pages worth of notes. I'm pretty sold on Scala. Now, all I need is a startup to hire me to write it ;) Learn how to be more productive with Scala, a new multi-paradigm language for the Java Virtual Machine (JVM) that integrates features of both object-oriented and functional programming. With this book, you'll discover why Scala is ideal for highly scalable, component-based applications that support concurrency and distribution. Programming Scala clearly explains the advantages of Scala as a JVM language. You'll learn how to leverage the wealth of Java class libraries to meet the practical needs of enterprise and Internet projects more easily. Packed with code examples, this book provides useful information on Scala's command-line tools, third-party tools, libraries, and available language-aware plugins for editors and IDEs.