=================================================================
Logtalk - Object oriented extension to Prolog
Release 2.27.1

Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
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% start by loading the necessary library support files (if not 
% already loaded):

| ?- logtalk_load([library(hierarchies_loader), library(types_loader)]).
...


% now you are ready for loading the example:

| ?- logtalk_load(sicstus(loader)).
...


% try some simple queries:


| ?- sort(rational)::sort([1/8, 2/7, 6/5, 2/9, 1/3], Sorted).

Sorted = [1/8, 2/9, 2/7, 1/3, 6/5]
yes


| ?- sort(colours)::sort([orange, indigo, red, yellow, violet, blue, green], Sorted).

Sorted = [red, orange, yellow, green, blue, indigo, violet]
yes


% using the pseudo-object user implies using the Prolog built-in standard 
% order operators:

| ?- sort(user)::sort([3, 1, 4, 2, 9], Sorted).

Sorted = [1, 2, 3, 4, 9]
yes


% some messages testing object parameter passing and using:

| ?- red_circle(3)::color(Color).

Color = red
yes


| ?- red_circle(3)::area(Area).

Area = 28.274334
yes


| ?- red_circle(3)::ancestors(As).

As = [circle(3, red), ellipse(3, 3, red)]
yes


% show the execution context using a method (context/3) that is defined in the
% hierarchy root and specialized (using super calls) in each descendant:

| ?- red_circle(3)::context.

red_circle1
self: red_circle(3)
this: red_circle(3)
sender: user

circle2
self: red_circle(3)
this: circle(3,red)
sender: user

ellipse3
self: red_circle(3)
this: ellipse(3,3,red)
sender: user

yes


% send a conjunction of messages/goals to an object; just some useful syntax 
% sugar:

| ?- square(2)::(side(Side), width(Width), height(Height), area(Area)).

Side = 2
Width = 2
Height = 2
Area = 4
yes


% find all messages accepted by an object:

| ?- square(2)::current_predicate(Pred).

Pred = side/1 ; 
Pred = width/1 ;
Pred = height/1 ;
Pred = area/1
yes


% find all data on a specific message accepted by an object:

| ?- square(_)::predicate_property(side(_), Prop).

Prop = public ;
Prop = static ;
Prop = declared_in(square(_133)) ;
Prop = defined_in(square(_164))
yes