Is the API good enough?

[slorber]

No description provided.

[yelouafi]

considering the example in README

const secondReducer = createReducer({ firstReducer },
  function (state = 0,action,{ firstReducer }) {
    return firstReducer + 1
  }
)

secondReducer doesn't react to any action, neither it needs any state; all it does is deriving some data from another; It appears more a selector than a reducer

[slorber]

yes maybe it's not the best example but I don't have any concrete usecase I'd like to solve :) (see reduxjs/redux#1315 (comment))