Slide 14.13: Prolog
Slide 14.15: Simple facts
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Using Prolog

  1. Check the Prolog Help Pages.

  2. There Are Two Ways to Execute Prolog Commands:
    3.
    • Interactive mode:
      •  Activate the Prolog interpreter and interactively execute Prolog commands. For example, 
       gandalf> gprolog

 GNU Prolog 1.2.19
 By Daniel Diaz
 Copyright (C) 1999-2005 Daniel Diaz

 | ?- write('Hello World!').
 Hello World!
 
 yes

 | ?- [user].

 {compiling user for byte code...}
 even(0).
 even(s(s(X))):-
         even(X).
 (here the user presses Ctl-D to end the input)
 {user compiled, 3 lines read - 350 bytes written, 1180 ms}
 
 | ?- even(X).
 
 X = 0 ? ;
 
 X = s(s(0)) ? ;
 
 X = s(s(s(s(0)))) ? (here the user presses RETURN to stop the execution)
 
 yes
 | ?- listing.
 
 even(0).
 even(s(s(A))) :-
         even(A).
 | ?- halt.

 gandalf>

    • Batch mode:
      •
      1. Create a Prolog program such as HelloWorld.pro .

      2. Compile the program. For example, 
         gandalf> gplc -o Hello  HelloWorld.pro

      3. Execute the program. For example, 
         gandalf> ./Hello

 GNU Prolog 1.2.19
 By Daniel Diaz
 Copyright (C) 1999-2005 Daniel Diaz

 | ?- hello.
 Hello, World!
 
 yes
 | ?- halt.

 gandalf>