title: How to update reducer with right state?
body: <p>In my react/redux app I have this reducer:</p>
  
  <pre><code>import {fromJS} from 'immutable';
  
  import {
    CHANGE_USERNAME,
    ADD_COUNTER
  } from './constants';
  
  // The initial state of the App
  const initialState = fromJS({
    username: '',
    counter:0
  });
  
  function homeReducer(state = initialState, action) {
    switch (action.type) {
      case CHANGE_USERNAME:
        // Delete prefixed '@' from the github username
        return state
          .set('username', action.name.replace(/@/gi, ''));
      case ADD_COUNTER:
        return state
          .set('counter',state.counter+1)
      default:
        return state;
    }
  }
  
  export default homeReducer;
  </code></pre>
  
  <p>Currently it hits the reducer but no state has been updated for the counter. What am I missing? link to <a href="https://github.com/dimitri-a/react-boilerplate/" rel="nofollow noreferrer">code</a></p>