For this, it seems worth trying Logtalk in order to lift Prolog programming to a different level (more contained). As usually, the first program show-casing some programming language is the famous "hello world" program. Unlike, other programming languages the Prolog version of "hello world" is a family relation.Logtalk is an object-oriented logic programming language that can use most
Prolog implementations as a back-end compiler. As a multi-paradigm language, it includes support for both prototypes and classes, protocols (interfaces), component-based programming through category-based composition, event-driven programming, and high-level multi-threading programming.
Since this post is merely to maintain flow, I will present a "hello world" in Logtalk. Logtalk helps decomposing program logic by offering the well known concept of object and interface (including visibility of object members).
Behold .. the magic "hello world":
:- object(first_program).
:- public(main/1).
hello_world(Text) :- write(Text), nl.
main(Text) :-
hello_world(Text).
:- end_object.
As can be guessed, the program is quite simple. An object called first program is declared,
offering a publicly visible method called main. main passes one argument, i.e. some text to print, to the famous hello_world procedure. hello_world calls Prolog's write function to write the passed text on some line, adding a newline at the end of the text.
After consulting the program, one may call main using
first_program::main('Hello World').
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