A simple thing can be difficult because understanding why it works may be nontrivial. However, it remains simple (by definition) if understanding is not affecte

A simple thing can be difficult because understanding why it works may be nontrivial. However, it remains simple (by definition) if understanding is not affected by complecting factors such as side-effects or the global state of the system. A pure function is always simple, even if it implements a difficult algorithm. I hold the opinion that complicated things can never be truly easy: they can only have the appearance of ease until there comes a time that you must understand all the complexity.