io7m
io7m-jtensors 6.0.2
2.4
Subclassing
1
The types in the jtensors package are not marked as final, despite all of their methods being final. The intention is to allow users of the types to subclass them with the intention of adding "phantom" type parameters [5] in order to distinguish between semantically distinct (but structurally identical) values at compile time.

[5]
http://io7m.com/documents/java/tt1-pt/