Hands-On Design Patterns with React Native

Pure functions in Redux

The good news is we can push side-effects to one place of our application and call them in a loop when we really need them. This is what Flux does. Redux embraces it even further, allowing only pure functions as reducers. This is understandable. Reducers are called when the impure part is already done. From there on, we can maintain immutability, at least in terms of the Redux stores.

Some may question whether this is a good choice in terms of performance. Trust me, it is. We have a really low number of events happening (that need to be reduced, and hence affect the store) in comparison with state accesses and selectors operating on the computed state.

In return for keeping the state immutable, we get a huge benefit. ...