title: Returning default value from function when result is error
body: <p>Is there something similar to the <code>?</code> shortcut which instead of returning a result from a function when there is an error, returns a predefined value?</p>
  
  <p>Basically I want to know if it is possible to do the following in one line:</p>
  
  <pre><code>fn index() -&gt; String {
      let temp = some_func("pass"); // some_func returns a Result 
      if temp.is_err() {
          return "No parameters named pass".to_string();
      }
      try_decrypt_data(temp.unwrap())
  }
  </code></pre>
  
  <p>I tried using <code>unwrap_or_else()</code>, but that just returns the closure not the outer function. i.e.</p>
  
  <pre><code>try_decrypt_data(params.get("pass").unwrap_or_else(|| return "No parameters named pass".to_string(); )) // This doesn't work
  </code></pre>