title: Why does interpolating a const string result in a compiler error?
body: <p>Why does string interpolation in c# does not work with const strings? For example:</p>
  
  <pre><code>private const string WEB_API_ROOT = "/private/WebApi/";
  private const string WEB_API_PROJECT = $"{WEB_API_ROOT}project.json";
  </code></pre>
  
  <p>From my point of view, everything is known at compile time. Or is that a feature that will be added later?</p>
  
  <p>Compiler message:</p>
  
  <blockquote>
    <p>The expression being assigned to 'DynamicWebApiBuilder.WEB_API_PROJECT' must be constant.</p>
  </blockquote>
  
  <p>Thanks a lot!</p>