The typeclass pattern in Scala invites you to place implementation-specific knowledge directly in the typeclass instances, with the interface defined as the typeclass’s abstract interface. However, GADTs permit a different organization of code. It is even possible to define a typeclass that seems to do nothing at all, yet still permits full type-safe typeclass usage. The possibilities between these two extremes form a design space. If you wish to practice ad-hoc polymorphism in Scala, this ...
