title: TypeError dispatcher.useState is not a function when using React Hooks
body: <p>I have this component:</p>
  
  <pre><code>import React, { useState, useEffect } from "react";
  import ReactDOM from "react-dom";
  
  function App() {
    const [count, setCount] = useState(0);
    useEffect(() =&gt; {
      document.title = `You clicked ${count} times`;
    });
  
    return (
      &lt;div&gt;
        &lt;p&gt;You clicked {count} times&lt;/p&gt;
        &lt;button onClick={() =&gt; setCount(count + 1)}&gt;Click me&lt;/button&gt;
      &lt;/div&gt;
    );
  }
  
  export default App;
  </code></pre>
  
  <p>as I want to try out the new <a href="https://reactjs.org/docs/hooks-intro.html" rel="noreferrer">React hooks</a> proposal by installing <code>react@16.8.1</code> in my <code>package.json</code>, but I'm getting an error:</p>
  
  <pre><code>TypeError: dispatcher.useState is not a function
  
    2 | import ReactDOM from "react-dom";
    3 | 
    4 | function App() {
  &gt; 5 |   const [count, setCount] = useState(0);
      |                                     ^
    6 |   useEffect(() =&gt; {
    7 |     document.title = `You clicked ${count} times`;
    8 |   });
  </code></pre>
  
  <p>What did I do wrong?</p>