Criterion 4 is: Red functions are more painful to call.

They are correct - this isn't a PL theory concept.

"More painful" is just being used to mean "explicit", and being explicit rather than implicit about intention is absolutely a PL theory concept, e.g. the whole difference between static and dynamic typing, or strong typing and weak typing.

	▲	dnautics 2 days ago \| parent [-]
		"Maybe it’s really verbose, or maybe you can’t do it inside certain kinds of statements. Maybe you can only call them on line numbers that are prime." Nope. If it's explicit but maybe like a single keyword away that's not "painful", I would guess.