Classes, fields, methods, constructors, and objects are the building blocks of object-based Java applications. This Java tutorial teaches you how to declare classes, describe attributes via fields ...

Java currently supports only primitive types and object references. Project Valhalla extends this by introducing inline classes which are new types that exhibit some behaviors of both types of value.

However, as a Java developer, this approach appeals to me because it is the most like Java (and other class-based object-oriented languages).