title: Observable Lists in flutter with mobx
body: <p>I am trying to make an observable list (i.e. when an element of the list is changed, removed, or added, I would like the UI to updated). I know that mobx has something called an "observableList", and so this seems like it should be possible. However, I am having issues implementing it. I currently have the following code in my mobx store file:</p>
  
  <pre><code>var metrics = Observable([.5,.5,.5]);
  </code></pre>
  
  <p>Then later, I try to change one of the elements like so:</p>
  
  <pre><code>metrics[index] = data;
  </code></pre>
  
  <p>I get the error:</p>
  
  <p><strong>The method '[]=' isn't defined for the class 'Observable>'.</strong></p>
  
  <p>Is there a way to create an observable list (or better yet, an observable dictionary) in flutter, or is that not implemented yet?</p>
  
  <p>Thanks!</p>