title: Prolog if/else statement with "or" condition
body: <p>I'm new to Prolog, and I'm trying to write an if/else statement with an "or" condition.  So to demonstrate, I want something like:</p>
  
  <pre><code> gothrough([H|T], B, C):-
      (  T == [] or H == 'then'  %if either the tail is an empty list or if H == "then", do the following%
      -&gt; append(H,B,B), outputs(B,C)
      ;  append(H,B,B), gothrough(T, B, C) %else%
      ).
  </code></pre>
  
  <p>This implementation doesn't work however; is there an obvious way to do this that I'm not getting?</p>
  
  <p>Thanks!</p>