- You can download the latest Java Development Kit (JDK) from Oracle. The minimum version required by Projog is Java 8. If using Ubuntu you can instead install Java using the command:
sudo apt-get install openjdk-8-jdk - After you have installed the JDK, from the command line enter
java -versionto confirm that Java is included in thePATHoperating system environment variable which specifies the set of directories where executable programs are located. - The latest version of Projog can be downloaded from the downloads page.
- Unzip the projog-0.10.0.zip file. This can be done using the command:
jar xvf projog-0.10.0.zip - From the command line change directory to the newly unzipped directory which will be named
projog-0.10.0 - If using Windows then run the
projog-console.batbatch script. If using Linux then make the startup script executable using the command:chmod u+x projog-console.shand then run it using the command:./projog-console.sh - From the
?-prompt you can use Prolog syntax to specify queries e.g.X is 1+1.and they will be evaluated. - You can enter
quit.at the?-prompt to exit the console. - If you provide the names of files, containing Prolog syntax, as arguments to the batch file or shell script e.g.
projog-console.bat towers-of-hanoi-example.plthen the files will be interpreted automatically when the console starts.
Examples
"Hello world" example.
?- write('hello, world'), nl.
hello, world
yesDynamically populate knowledge base with facts.
?- asserta(message(hi, world)).
yes
?- assertz(message(hello, everyone)).
yes
?- asserta(message(hello, world)).
yesQuery using new facts added to the knowledge base.
?- message(hello, everyone).
yes
?- message(hi, everyone).
no
?- message(X, Y).
X = hello
Y = world
yes;
X = hi
Y = world
yes;
X = hello
Y = everyone
yes
?- message(hello, Y).
Y = world
yes;
Y = everyone
yesSimple example of both unification and arithmetic.
?- W=X, X=1+1, Y is W, Z is -W.
W = 1 + 1
X = 1 + 1
Y = 2
Z = -2
yesPopulate the knowledge base with clauses read from a file containing Prolog syntax.
?- consult('towers-of-hanoi-example.pl').
yesView the definition of hanoi that has just been parsed from the consulted file.
?- listing(hanoi).
hanoi(N) :- move(N, left, centre, right)
yesUse the clauses loaded from towers-of-hanoi-example.pl in a query.
?- hanoi(2).
[move,a,disc,from,the,left,pole,to,the,right,pole]
[move,a,disc,from,the,left,pole,to,the,centre,pole]
[move,a,disc,from,the,right,pole,to,the,centre,pole]
yes