Discussion on: Are reducers split too specific?

Usually you have 1 reducer for your slice of state. In the reducer you update the state according to the action. Based upon the action you can update the state how you want.

You probably just want to define how you update the state in their own function if it gets really complex.

function GlossaryReducer(state, action) {
  switch(action.type) {
    //..
    case 'fetchGlossary':
      return fetchGlossary(state, action); // this returns the updated state
    //..    
  }
}

So you keep your 1 reducer, but split up the logic within that reducer with helper functions. This way your reducer just handles the glossary state, rather then having a reducer for each action as that removes the "middle" abstraction of having a reducer handle multiple actions relevant to the same piece of state.

PS. I use NGRX rather then Redux directly, but afaik the base api is the same. :)