3.4.2.1 Edit modes

Modes are the heart of (Pce)Emacs. Modes define dedicated editing support for a particular kind of (source) text. For our purpose we want Prolog mode. There are various ways to make PceEmacs use Prolog mode for a file.

• Using the proper extension
  If the file ends in .pl or the selected alternative (e.g. .pro) extension, Prolog mode is selected.

• Using #!/path/to/.../swipl
  If the file is a Prolog Script file, starting with the line #!/path/to/swipl options, Prolog mode is selected regardless of the extension.

• Using -*- Prolog -*-
  If the above sequence appears in the first line of the file (inside a Prolog comment) Prolog mode is selected.

• Explicit selection
  Finally, using File/Mode/Prolog you can switch to Prolog mode explicitly.