factorial(n:int) : int | effects [] {
	int acc = 1; {effect [write acc]}                     | {effect [write acc]}

	for ( int i = 1; {effects [write i]}                   | {effect [write i, write acc]}
			i <= n; {effects [read i, read n]}             | {effect [write i, read i, write acc]}
			i++ {effects [read i, write i]} ){             | {effect [write i, read i, write acc]}
		acc *= i; {effects [read i, read acc, write acc]}  | {effect [write i, read i, write acc]}
	}                                                      | {effect [read acc, write acc]} //i goes out of scope, so its effects are dropped
                                                           | {effects [read acc]}
	return acc;                                            | {effects []} //acc goes out of scope
}