Introducing type parameters #6
Description
I haven't thought about this too much yet, but we might be able to introduce type parameters for input and output. Maybe something like Command[-I, +O]? And then provide evidence where it makes sense (like for "this operation only makes sense on List[String] and so on).
That's what I got from when @jdegoes briefly mentioned it, but please correct me if I misinterpreted something.