Scala is a general purpose programming language. Scala is an acronym for Scalable Language. This reflects the vision of its creators of making Scala a language that grows with the programmer's experience of it. The fact that Scala and Java objects can be freely mixed makes transition from Java to Scala quite easy.

Scala is also a full-blown functional language. Unlike in other languages, such as Haskell, which is a pure functional language, Scala allows interoperability with Java and support for object-oriented programming. Scala also allows the use of both pure and impure functions. Impure functions have side effects such as mutation, I/O, and exceptions. The purist approach to Scala programming encourages the use of pure functions only.

Scala is a type-safe JVM language that incorporates both object-oriented and functional programming in an extremely concise, logical, and extraordinarily powerful language.

Here are some advantages of using Scala:

Scala Build Tool (SBT) is a build tool that allows the compiling, running, testing, packaging, and deployment of your code. SBT is mostly used with Scala projects, but it can as easily be used for projects in other languages. In this book, we will be using SBT as a build tool for managing our project and running our tests.

SBT is written in Scala and can use many of the features of the Scala language. Build definitions for SBT are also written in Scala. These definitions are both flexible and powerful. SBT also allows the use of plugins and dependency management. If you have used a build tool such as Maven or Gradle in any of your previous incarnations, you will find SBT a breeze.

The following are the reasons we choose SBT:

Here are a few of the resources for learning Scala:

Here are a few of the resources for learning SBT:

We have done enough jibber-jabber to lay the groundwork for getting our hands on the driving plates now. Let's start with setting up the environment so we can write, compile, and run a test-driven application using Scala and SBT.

This is the barebone setup you need to write in order to create a very trivial project that builds using SBT.

There is a default project directory structure for SBT projects that defines where SBT will look for application code and tests. By default, SBT uses a similar directory structure to Maven:

SBT uses build.sbt as a default build definition file. There are other variations of build definition files, such as .scala and multi-project files. For the scope of this book, we will only look at the build.sbt definition file.