That is a very good question. Currently effects are outside the typesystem, but I'm planning on adding an algebraic effect system similar to the one used in Microsoft's Koka language.
Morlock's are also the creatures that manage the machines under the world in Well's Time Traveler novel. Though I guess they are known more for their dietary preferences.
A proper reply to this comment would fill a very long blog post, and I'm currently on vacation, so I'll have to get back to you later.