[Skeime]

Having a situation where one handles both `Nothing` and `Just Nothing` in the same context should be rare.

But you might be writing some functions on some abstract data structure with a type parameter `a` (say it’s a graph and users can tag the vertices with values of type `a`). And (maybe just internally) there are situations in your algorithms where a value might be absent, so you use `Maybe a`. If `Nothing == Just Nothing`, your Users can’t use a maybe type for `a` anymore because your algorithm wouldn’t be able to distinguish between its `Nothing`s and the user’s.