title: Why is there no built-in Set data type in Haskell?
body: <p>Is there anyone who can explain to me why there's no <code>Set</code> datatype defined in Haskell? </p>
  
  <p>Sidenote:
  I'm only learning Haskell as part of a course on logic in which set theory is very important thus it would be really handy to have the notion of a set in Haskell. Having a list and removing duplicates (and possibly sorting) would result in a set as well but I'm curious if there's a particular reason why it's not built-in? </p>