Use the selector pattern?
I'm quoting from our code review here:
Every Redux reducer module should export the reducer itself as default and multiple functions for providing access to state as named exports. These functions are called “selectors” and encapsulate the knowledge about the shape of the state tree in one place, near where that shape is defined (i.e. the reducer). For example, in pubsweet-client/src/reducers/collections.js, add:
export const getCollections = state => state.collections
And access state elsewhere through this function.
See https://gist.github.com/abhiaiyer91/aaf6e325cf7fc5fd5ebc70192a1fa170