Many of those things can be modelled as functions, they just need to actually be written that way (e.g. if you have a function that requires some resource, mayb

Many of those things can be modelled as functions, they just need to actually be written that way (e.g. if you have a function that requires some resource, maybe it should require that resource! If it depends on the date/time, maybe it should depend on the date/time! If it returns a nondeterministic value, maybe it should return a nondeterministic value!). I think the functional programming approach shines partly because it forces you to take these things seriously: if you want to use e.g. implicitly shared resources, you need to model that, and "functions" that rely on implicitly shared resources are going to be explicitly distinct from actual function functions.