> Inheritance and interfaces are relationships between classes. But what about relationships between functions? Classes ARE functions. Conceptually, they are c

> Inheritance and interfaces are relationships between classes. But what about relationships between functions? Classes ARE functions. Conceptually, they are closures with some automatically generated features and language semantics. https://www.youtube.com/watch?v=mrY6xrWp3Gs https://www.youtube.com/watch?v=mrY6xrWp3Gs Classical inheritance is BAD and you wouldn't want that kind of relationship for functions. Ofc, what the article suggests is basically assertions - why execute code once, when you can do it twice!? Modern languages should have function signatures. After I write tests (a full testing framework should also be native to a language), being able to get a function signature which ensures a pairing with a specific set of tests would be great. No more side effects added in without breaking tests, ensuring you would have to make a test change, even if it's introducing some new side effect that doesn't break an existing test.