These are some exercises that introduce some of Prolog's core concepts. Get started by cloning the repo:
$ git clone git@github.com:Futurelearn/prolog_learning_hour.git
$ cd prolog_learning_hour
There are many different Prolog implementations - the exercises require one called SWI-Prolog.
For Macs, assuming you've got homebrew already installed:
$ brew install swi-prolog
If you're using Ubuntu 17.04 or later, swi-prolog is available in the default repositories:
$ sudo apt-get update
$ sudo apt-get install swi-prolog
I believe (but have not verified) that on earlier Ubuntu systems the following will work instead:
$ sudo add-apt-repository ppa:swi-prolog/stable
$ sudo apt-get update
$ sudo apt-get install swi-prolog
Prolog files use a .pl extension. Unfortunately this is also used by
Perl, so by default your editor will probably try to highlight the
exercise code as Perl. Prolog was first, though, by some 15 years. Get
off my lawn.
To get proper syntax highlighting, here are some plugins for different editors:
Vim and emacs should work just fine because, naturally, these editors ship by default with syntax for all of the 70s languages.
There are three sets of exercises:
- Facts, rules and queries -
src/facts_rules_and_queries.pl - Family tree -
src/genealogy.pl - Peano numbers -
src/peano.pl
Work through them in order - but don't worry if you don't have time to finish! I've tried to make sure there's more than enough to be getting on with.
Each file contains its own instructions and a number of exercises. Some
of these will ask you to run queries at the console, which you can do
with make console - this will automatically load all code in the
exercise files so you can query your programs:
$ make console
?- parent(mildred, bob).
true.
?-
Other exercises ask you to define new facts or rules, which you can write directly in the exercise files where indicated. If you want to try out your changes at the console, you can reload your code like so:
?- reload.
true.
?-
For the genealogy and peano exercises, there are some pre-written tests, which you can run from the command line:
$ make genealogy
< lots of yelling output >
$ make peano
< lots of yelling output >
To see the tests themselves, look at test/genealogy_test.pl and
test/peano_test.pl. The test output for failures isn't very friendly -
rspec-style delights haven't quite found their way into Prolog just yet.
Please ask questions freely whenever something's not clear. :-)