In languages such as Java, there is no direct support for value objects. What developers end up doing is to declare the fields as final and implement the hashCode and equals methods.
Immutability, however, is a concept that is pretty much enforced in Scala. We already saw the algebraic data types (ADTs) earlier—they also fall in the value object category. Case classes and tuples are also immutable and they are used to achieve the value object design pattern. The following class diagram shows an example of the value object design pattern in Scala:
This diagram really doesn't do anything special. It is a representation ...
