How do I set Aquamacs to use Prolog mode?

Question

I'm new to Emacs/Aquamacs, and want to use it to program in Prolog. My filename ends with ".pl" and Aquamacs automatically assumes it's a Perl file. How do I change it to use Prolog mode instead? I'd prefer an answer that doesn't assume I know how to get around in Emacs at all.

Under Preferences -> Programming -> Languages. I cannot find Prolog, even though the Aquamacs webpage states it's supposed to support Prolog? Do I need to install some addon?

Answer 1

You can activate Prolog mode manually with M-x prolog-mode.

I have the following line in my Emacs configuration file (usually referred to as .emacs, though I personally use the alternative location .emacs.d/init.el) to make it the default for .pl files:

(add-to-list 'auto-mode-alist '("\\.pl\\'" . prolog-mode))