The name Scala comes from a scalable language because Scala's concepts scale well to large programs. Some programs in other languages will take tens of lines to be coded, but in Scala, you will get the power to express the general patterns and concepts of programming in a concise and effective manner. In this section, we will describe some exciting features of Scala that Odersky has created for us:
Scala: the scalable language
Scala is object-oriented
Scala is a very good example of an object-oriented language. To define a type or behavior for your objects you need to use the notion of classes and traits, which will be explained later, in the next chapter. Scala doesn't support direct multiple inheritances, but to achieve this structure, you need to use Scala's extension of the subclassing and mixing-based composition. This will be discussed in later chapters.
Scala is functional
Functional programming treats functions like first-class citizens. In Scala, this is achieved with syntactic sugar and objects that extend traits (like Function2), but this is how functional programming is achieved in Scala. Also, Scala defines a simple and easy way to define anonymous functions (functions without names). It also supports higher-order functions and it allows nested functions. The syntax of these concepts will be explained in deeper details in the coming chapters.
Also, it helps you to code in an immutable way, and by this, you can easily apply it to parallelism with synchronization and concurrency.
Scala is statically typed
Unlike the other statically typed languages like Pascal, Rust, and so on, Scala does not expect you to provide redundant type information. You don't have to specify the type in most cases. Most importantly, you don't even need to repeat them again.
A programming language is called statically typed if the type of a variable is known at compile time: this also means that, as a programmer, you must specify what the type of each variable is. For example, Scala, Java, C, OCaml, Haskell, and C++, and so on. On the other hand, Perl, Ruby, Python, and so on are dynamically typed languages, where the type is not associated with the variables or fields, but with the runtime values.
The statically typed nature of Scala ensures that all kinds of checking are done by the compiler. This extremely powerful feature of Scala helps you find/catch most trivial bugs and errors at a very early stage, before being executed.
Scala runs on the JVM
Just like Java, Scala is also compiled into bytecode which can easily be executed by the JVM. This means that the runtime platforms of Scala and Java are the same because both generate bytecodes as the compilation output. So, you can easily switch from Java to Scala, you can and also easily integrate both, or even use Scala in your Android application to add a functional flavor.
Note that, while using Java code in a Scala program is quite easy, the opposite is very difficult, mostly because of Scala's syntactic sugar.
Also, just like the javac command, which compiles Java code into bytecode, Scala has the scalas command, which compiles the Scala code into bytecode.
Scala can execute Java code
As mentioned earlier, Scala can also be used to execute your Java code. Not just installing your Java code; it also enables you to use all the available classes from the Java SDK, and even your own predefined classes, projects, and packages right in the Scala environment.
Scala can do concurrent and synchronized processing
Some programs in other languages will take tens of lines to be coded, but in Scala, you will get the power to express the general patterns and concepts of programming in a concise and effective manner. Also, it helps you to code in an immutable way, and by this, you can easily apply it to parallelism with synchronization and concurrency.
