% Base case: The factorial of 0 is 1.
factorial(0, 1).
% Calculate factorial using an accumulator.
factorial(N, Result) :-
N > 0,
factorial(N, 1, Result).
% Recursive rule with an accumulator.
factorial(1, Accumulator, Accumulator).
factorial(N, Accumulator, Result) :-
N > 1,
N1 is N - 1,
NewAccumulator is Accumulator * N,
factorial(N1, NewAccumulator, Result).
% Example usage:
% To calculate the factorial of 5, you can query:
% ?- factorial(5, X).
% X will be unified with the value 120. Write, Run & Share Prolog code online using OneCompiler’s Prolog online compiler for free. It’s a simple and intuitive platform to experiment with logic programming in Prolog. OneCompiler supports standard Prolog syntax, great for learning, prototyping, and practicing logic-based problems.
Prolog (Programming in Logic) is a logic programming language associated with artificial intelligence and computational linguistics. It works through facts, rules, and queries, using a form of symbolic reasoning known as backward chaining. Prolog is declarative, meaning you describe what you want instead of how to compute it.
The following is a simple Prolog program that prints a greeting:
:- initialization(main).
main :-
write('Hello, World!').
Facts represent basic assertions about the world.
likes(alice, pizza).
likes(bob, pasta).
Rules define logical relationships using facts.
friends(X, Y) :- likes(X, Z), likes(Y, Z).
Queries are used to find information based on facts and rules.
?- likes(alice, What).
| Operator | Description |
|---|---|
:- | Rule definition |
, | Logical AND |
; | Logical OR |
= | Unification |
member(X, [X|_]).
member(X, [_|T]) :- member(X, T).
Prolog heavily relies on recursion.
factorial(0, 1).
factorial(N, F) :-
N > 0,
N1 is N - 1,
factorial(N1, F1),
F is N * F1.
This guide provides a quick reference to Prolog programming syntax and features. Start writing Prolog code using OneCompiler’s Prolog online compiler today!