title: What is a type and effect system?
body: <p>The <a href="http://en.wikipedia.org/wiki/Effect_system" rel="noreferrer">Wikipedia article on <em>Effect system</em></a> is currently just a short stub and I've been wondering for a while as to what is an effect system. </p>
  
  <ul>
  <li>Are there any languages that have an effect system in addition to a type system?  </li>
  <li>What would a possible (hypothetical) notation in a <strong>mainstream</strong> language, that you're familiar, with look like with effects? </li>
  </ul>