> An alternative is to take a typeclass-like view.
Type classes alone don't give you anything like Go's interfaces.
Type classes plus existentials give you something kinda like Go's interfaces, but requires explicit casts (in the form of unwrapping the contents of an existential constructor and putting them into another existential constructor).
Type classes plus rank-N types can express Go's interfaces, but at that point Haskell already has subtyping, induced by subclasses. (Or else how do you think “a Lens is a Traversal” is possible?)
