## 3.9 Summary of the IDE

The SWI-Prolog development environment consists of a number of interrelated but not (yet) integrated tools. Here is a list of the most important features and tips.

- Atom completion
  The console41On Windows this is realised by swipl-win.exe, on Unix through the GNU readline library, which is included automatically when found by configure. completes a partial atom on the `TAB` key and shows alternatives on the command `Alt-?`.

- Use edit/1 for finding locations
  The command edit/1 takes the name of a file, module, predicate or other entity registered through extensions and starts the user's preferred editor at the right location.

- Select editor
  External editors are selected using the `EDITOR` environment variable, by setting the Prolog flag editor, or by defining the hook qpredrefprolog_editedit_source1.

- Update Prolog after editing
  Using make/0, all files you have edited are re-loaded.

- PceEmacs
  Offers syntax highlighting and checking based on real-time parsing of the editor's buffer, layout support and navigation support.

- Using the graphical debugger
  The predicates guitracer/0 and noguitracer/0 switch between traditional text-based and window-based debugging. The tracer is activated using the trace/0, spy/1 or menu items from PceEmacs or the Prolog Navigator.

- The Prolog Navigator
  Shows the file structure and structure inside the file. It allows for loading files, editing, setting spy points, etc.