I think Alvaro's at the Unison conference was a pretty cool demonstration of what you can do with the style of algebraic effects (called "abilities" in unison)

https://www.youtube.com/watch?v=u5nWbXyrC8Y

He implements an erlang style actor system, and then by using different handlers for the algebraic effects, he can "run" the actor system, but also optionally make a live diagram of the actor communications.