Inheritance is usually really great when you want to extend the type outside the context it was created in. GUI is a very clear example of that where compositio

Inheritance is usually really great when you want to extend the type outside the context it was created in. GUI is a very clear example of that where composition may work but is greatly tedious (reimplementing the whole interface, exposing it, and rewiring), and sum types are right off the bat inapplicable.