So we are now getting pretty close to accomplishing yet another architectural problem that we set out to solve at the beginning of this series of episodes. We stated that we wanted to be able to build large complex applications out of simple, composable units.

We can now do this with our reducers and the state they operate on. We can write our reducers so that they operate on just the bare minimum of state necessary to get the job done, and then pull them back to fit inside a reducer that is much larger and operates on a full application’s state.

Ideally we’d even want those simple, composable units to be so isolated that we may even be able to put them in their own module so that they could easily be shared with other modules and apps.

This is getting pretty exciting! But, there’s still a problem. Even though our reducers are operating on smaller pieces of data, they still know far too much about the larger reducer they are embedded in, particularly they can listen in on every single app action.

It sounds like we need to repeat the same story for actions that we have for state.