Haskell inheritance: What's inherity about it?

In practice, this means that all members of the subclass necessarily provide all methods of the superclass.

So, as in the linked example, we can write a method that requires Eq, but only give it an Ord constraint, and the Eq methods are implied for us.

(Note that inheritance is probably a terrible term for this, because it carries a lot of associations that don't make sense in our context. Nonetheless, I figured I might as well explain it.)