• The PDT is released under the terms of the Eclipse Public License(EPL).

1. JDK/JRE (at least version 1.7.X)
2. Eclipse (at least version 4.6 /Neon)
3. SWI-prolog for your platform (at least version 6.6.0). Please follow carefully the instructions for installing on your specific operating system.
4. Make sure that the path to each of the above executables is in your PATH environment variable.
5. Test your SWI-Prolog installation: In a terminal window, type
   • swipl ← If the SWI-Prolog command line does not start in your terminal, your PATH variable is not properly set up.
   • swipl-win ← If no separate window opens for SWI-Prolog, X11 is not installed properly, or not running, or the DISPLAY variable might not point to the X11 server.
6. If either of the two tests fails, see the troubleshooting section.

After having fulfilled the above Prerequisites:

• Add the PDT Update Site to your Eclipse installation by entering on of the following URLs

in “Help” → “Install new Software…” → “Add…”:

• Select the “PDT” feature. This is how it should look (except for the version number):

• Press “Next” and follow the instructions.
• If you get stuck and the dialog shows the message “Calculating requirements and dependencies” you should uncheck the “Contact all update sites during install…” option. Please note that this is only possible if you used one of the recommended Eclipse configurations (see prerequisites).

• New to the PDT? → Read Getting Started and Overview.
• PDT pro? → Read Release Notes.

1. All platforms: If you get PrologProcessException errors (containing messages such as “Failed to obtain session”, “Timout exceeded while waiting for peer to come up”, etc.) SWI-Prolog cannot be started from Eclipse. Then make sure that
   • SWI-Prolog is installed,
   • the SWI-Prolog executable “swipl-win” is in your path,
   • your firewall does not block connections from Eclipse / Java to Prolog
   • on MacOS: the X11 environment (XQuartz) is installed and running and the DISPLAY variable is properly set (see also the note below).
2. MacOS / Linux: If the graphical tracer does not start (or any other part of SWI-Prolog that need the XQuartz / X11 environment):
   1. Install the X11 environment
   2. Set the DISPLAY variable properly:
      • Open a terminal window
      • Type “echo $DISPLAY”
      • Copy the result line that is displayed
      • Open the PDT preferences (Preferences > PDT > Prolog Processes)
      • Select your current configuration on the right-hand side and click “Edit”
      • Enter “DISPLAY=…what you copied…” into the “Extra environment variables” field
      • If there are more entries there, separate them by a comma (,)
   3. Always make sure X11 is running before you start the PDT!!!