Detection of optional dependencies

[NeQuissimus]

With sbt's optional dependencies, it is possible to write code against type classes that may or may not exist downstream.

See
https://blog.7mind.io/no-more-orphans.html

It would be great to have common HasCats, HasScalaz marker traits.

[alexandru]

@NeQuissimus that would be really cool.

Guess I'll have to study that article in more detail to see how it would work.

[NeQuissimus]

I tried it briefly and it seems OK to have an object that has an implicit class. But once you have alternative implicit classes for the same A, you always run into diverging implicits, I had some trouble with that.