title: How can I use a GUI debugger on the Prolog code that runs inside a Java app through JPL?
body: <p>I'm developing a Java+Prolog application through the JPL bridge. The main application is in Java and it calls the Prolog code using <code>Query.oneSolution("doPrologStuff(here)")</code></p>
  
  <p>I tried running the GUI debugger/tracer using <code>Query.hasSolution("gtrace")</code> but it throws an exception:</p>
  
  <pre><code>Exception in thread "main" jpl.PrologException: PrologException: error(existence_error(procedure, /(gtrace, 0)), context(:(system, /('$c_call_prolog', 0)), _0))
      at jpl.Query.get1(Query.java:336)
      ...
  </code></pre>
  
  <p>(Same goes for "guitracer")</p>
  
  <p>Calling <code>gtrace.</code> works well when I run the Prolog code in <code>swipl</code> directly.</p>
  
  <p>When I try <code>Query.hasSolution("trace")</code> it lets me debug the code using the text console, but that's not what I'm looking for. Any ideas how to enable the GUI debugger?</p>
  
  <p>I'm using Eclipse on Ubuntu to develop, but I can try other tools if that helps :)</p>