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This file is part of Logtalk https://logtalk.org/ SPDX-FileCopyrightText: 1998-2023 Paulo Moura <pmoura@logtalk.org> SPDX-License-Identifier: Apache-2.0

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

% start by loading the example:

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

% print a list of books that have extras:

| ?- data_processing::print.

The Philosopher's Stone with free quidditch_set at 278 gr The Chamber of Secrets with free map The Prisoner of Azkaban The Goblet of Fire The Order of the Phoenix The Half-Blood Prince with free audio_cd The Deathly Hallows with free horcrux_set at 123 gr yes

% print variant using kilograms instead of grams by mapping optionals:

| ?- data_processing::print_kg.

The Philosopher's Stone with free quidditch_set at 0.278 kg The Chamber of Secrets with free map The Prisoner of Azkaban The Goblet of Fire The Order of the Phoenix The Half-Blood Prince with free audio_cd The Deathly Hallows with free horcrux_set at 0.123 kg yes

% print a list of extras with declared weight

| ?- data_processing::print_heavy_extras.

quidditch_set at 278 gr horcrux_set at 123 gr yes

% get a list of book titles that have extras:

| ?- data_processing::books_with_extras(Titles).

Titles = ['The Philosopher\'s Stone', 'The Chamber of Secrets', 'The Half-Blood Prince', 'The Deathly Hallows'] yes