Assuming a is an expression, which could well be a call to a function, then the two are equivalent. Note that the argument here is one of declarativeness vs im

Assuming a is an expression, which could well be a call to a function, then the two are equivalent. Note that the argument here is one of declarativeness vs imperativeness, i.e. whether it is at all practically possible to ever have programs that have zero need for control flows. It is not one of whether a() is a pure vs a stateful function.