Combining reducers into one

combine_reducers.rb

class ReduxStore
  def self.combine_reducers(reducers)
    -> (state, action) {
      state ||= {}

      reducers.reduce({}) { |next_state, (key, reducer)|
        next_state[key] = reducer.call(state[key], action)
        next_state
      }
    }
  end
end