Consider to use InstanceOf scalaz pattern

[Odomontois]

This scalaz PR targeting well-known ambigous-subtype implicit problem resolving it without repackaging base typeclass instances inside sub-typeclass es.

I wonder if this method is suitable for cats-mtl project.

PR welcome?

[LukaJCB]

This sounds like a good idea to me, I haven't fully understood the pattern yet, but it seems to strike a good balance. We've always said cats-mtl is an experimental part of the ecosystem, so I'd love to see a PR :)

[SystemFw]

Yes, we should definitely see where this leads.

[andyscott]

Agreed! PR is definitely welcome.

[LukaJCB]

I wonder if we could get an experimental version of simulacrum with this type of encoding

[LukaJCB]

@Odomontois, are you working on this? If not I'd like to give this a shot.

[kamilkloch]

@LukaJCB I picked up the task.

[LukaJCB]

Closing in favor of #53