title: Sort list of lists in R: sort one lists' value depending on other lists' value
body: <p>I need some help with sorting a list of lists. Suppose I have a list of children given as following:</p>
  
  <pre><code>a &lt;- list(name = "Ann", age = 9)
  b &lt;- list(name = "Bobby", age = 17)
  c &lt;- list(name = "Alex", age = 6)
  
  my.list &lt;- list(a, b, c)
  </code></pre>
  
  <p>I would like to sort their names by their age, so receive the following:</p>
  
  <pre><code>&gt; "Alex" "Ann" "Bobby"
  </code></pre>