If you were using redux-define you could reduce the boilerplate of defining action types.
Especially when using status suffixes like ERROR or SUCCESS, it can make a big difference.
Turning your example
export const ADD_TODO = 'todos/ADD_TODO'
export const ADD_TODO_SUCCESS = 'todos/ADD_TODO_SUCCESS'
export const ADD_TODO_FAILURE = 'todos/ADD_TODO_FAILURE'
Into
export const ADD_TODO = defineAction('ADD_TODO', [SUCCESS, FAILURE], 'todos');