The backbone of the Scala language is variables and functions.
The variables are defined as follows:
scala> var foo = 3
foo: Int = 3
Variables are defined using the var keyword followed by the name of the variable, followed by the value you would like to assign to the variable.
Variables defined in the preceding manner are mutable. This means that once they are assigned, you can modify them:
scala> var foo = 3
foo: Int = 3
scala> foo = 20
foo: Int = 20
However, purely functional programming advocates against this style. Since Scala positions itself as a mixture of purely functional and object-oriented styles, it offers a way to define an immutable variable:
scala> val bar = 3
bar: Int = 3
Now, if you try to modify is this variable, you will get a compile-time error:
scala> val bar = 3
bar: Int = 3
scala> bar = 20
<console>:12: error:...
