title: mix redux-thunk with redux-observable
body: <p>I have an app using redux-thunk and want to try out redux-observable.
  Currently I have a thunk action creator that does the following:</p>
  
  <pre class="lang-js prettyprint-override"><code>const initState = () =&gt; {
      return dispatch =&gt; new Promise((resolve,reject)=&gt;{
          //these each return axios promises as they get data from the server
          const pr1 = dispatch(processData1())
          const pr2 = dispatch(processData2())
          Promise.all([pr1,pr2])
              .then(r=&gt;resolve(true))
              .catch(e=&gt;reject(e))
          })
      }
  }
  </code></pre>
  
  <p>and this is called from my component in componentDidMount like so:</p>
  
  <pre class="lang-js prettyprint-override"><code>this.props.initState()
      .then(r=&gt;this.setState({loaded:true}))
      .catch(e=&gt;this.setState({loadError:true}))
  </code></pre>
  
  <p>Now I want to try redux-observable Can I combine it with redux-thunk and replace the <code>processData2()</code> call to instead dispatch an action which is dealt with by redux-observable?
  i.e.</p>
  
  <pre class="lang-js prettyprint-override"><code>const pr2 = dispatch({type:OBSERVABLE_PROCESSDATA2})
  </code></pre>
  
  <p>Now as far as I can tell, this isn't going to return a promise so the original code will now break as in <code>Promise.all</code> will <code>.then(r=&gt;resolve(true))</code> immediately even though redux-observable epic has not yet processed it.
  So is there a way I can wait for that dispatch to do the async stuff in the epic or do I need to basically go redux-observable all the way in this case?</p>