title: How to find the index of an element in a list?
body: <p>Giving an element in a list, which function can I use to find its index?</p>
  
  <p>For instance, I want to find the index of 3 in the list <code>[1, 2, 3, 4]</code>.</p>
  
  <p>Which function exists in Haskell that I can use for this?</p>