export const id = a => a;

export const registerSubscriptions = subscriptionsArray => fn => {
	subscriptionsArray.push(fn);
	return () => {
		const idx = subscriptionsArray.indexOf(fn);
		if (idx !== -1) {
			subscriptionsArray.splice(idx, 1);
		}
		return subscriptionsArray.length;
	};
};

export const call = a => (typeof a === 'function' ? a() : a);

export const registerFire = subscriptionsArray => val => {
	subscriptionsArray.map(s => s(val)).forEach(call);
};