Monads are simple to understand.

You can just think of them like a fleet of mysterious inverted pyramids ominously hovering over a landscape dotted with the tombs of ancient and terrible gods. Tombs from which they may awake at any moment if they are “evaluated”.

The IO loop is then the malevolent personification of the force of entropy, causing every action we take to push the universe further into the depths of uncontrolled chaos.

Simple!