code.es6

const applier = (rules, reactions) => {
	const apply = (state, events) => {
		return R.reduce((state, event) => {
			const reaction = reactions(state, event);
			const next = rules(state, event);

			return apply(next, reaction);
		}, state, events);
	};

	return apply;
};

same.rs

fn apply<T, S, A, R, I: Iterator<Item=&S>> (applier: &A, reactor: &R, initial_state: T, signals: I) -> T where
	A: FnMut(&T, &S) -> T,
	R: FnMut(&T, &S) -> Iterator<Item=S> {

	return signals
		.iter()
		.fold(initial_state, |state, signal| {
			let reaction = reactor(&state, &signal);
			let next_state = applier(&state, &signal);

			return apply(applier, reactor, next_state, reaction);
		});
}

fn main() {
    let app = |st, sig| {
        return st + sig;
    };

    let reatc = |st, sig| {
        return 0..st;
    };

    let r = apply(&app, &reatc, 0, 1..5);
}