title: How to download a large file with hyper and resume on error?
body: <p>I want to download large files (500mb) with hyper, and be able to resume if the download fails. </p>
  
  <p>Is there any way with hyper to run some function for each chunk of data received? The <code>send()</code> method returns a <code>Result&lt;Response&gt;</code>, but I can't find any methods on <a href="http://hyper.rs/hyper/0.8.0/hyper/client/response/struct.Response.html" rel="nofollow noreferrer">Response</a> that return an iterator over chunks. Ideally I'd be able to do something like:</p>
  
  <pre><code>client.get(&amp;url.to_string())
      .send()
      .map(|mut res| {
          let mut chunk = String::new();
          // write this chunk to disk
      });
  </code></pre>
  
  <p>Is this possible, or will <code>map</code> only be called once hyper has downloaded the entire file?</p>