title: Lua language: how use something similar to python list comprehensions
body: <p>I'm new to Lua and I was wondering if there are some compact way to define a <code>list</code>, a <code>metatable</code> in Lua as we do in Python:</p>
  
  <pre><code>lis = [i for i in set if i&gt;0]
  </code></pre>
  
  <p>Any example would be greatly appreciated.</p>