Justin2.m

// A nice little example of using transactional signal generators.
// Imagine a board of buttons with numbers on it, and a big red button with a picture of a bomb on it.
// When a button with a number is pressed, `increment` is invoked with that number. When the bomb
// button is pressed, then `reset` is invoked.
//
//This returns a signal of the running total made by incrementing by numbers and resetting by explosions.
RACDynamicSignalGenerator *increment = [[RACDynamicSignalGenerator alloc] initWithBlock:^RACSignal *(NSNumber *add) {
	return [RACSignal return:^(NSNumber *count) {
		return @(count.integerValue + add.integerValue);
	}];
}];

RACDynamicSignalGenerator *reset = [[RACDynamicSignalGenerator alloc] initWithBlock:^RACSignal *(id _) {
	return [RACSignal return:^(NSNumber *count) {
		return @0;
	}];
}];

RACSignal *transformers = [RACSignal merge:@[ increment.asTransactionSignalGenerator.transactions.flatten,
					      reset.asTransactionSignalGenerator.transactions.flatten ]];
return [transformers scanWithStart:@0 reduce:^id(NSNumber *count, NSNumber *(^transformer)(NSNumber *)) {
	return transformer(count);
}];