________________________________________________________________________

This file is part of Logtalk <https://logtalk.org/>  
SPDX-FileCopyrightText: 1998-2026 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
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`permutations`
==============

This library provides predicates for generating and querying permutations
over lists. The following categories of predicates are provided:

* **Generation operations** - Predicates for generating permutations and k-permutations.
* **Ordering variants** - Predicates that support an additional order argument (`default`, `lexicographic`, or `shortlex`) for controlling output order.
* **Distinct-value generation** - Predicates for generating permutations while deduplicating equal-valued results.
* **Lexicographic stepping** - Predicates for navigating permutations in lexicographic order.
* **Indexed access** - Predicates for direct access to permutations at specific positions, including distinct permutations.
* **Counting operations** - Predicates for counting permutations and distinct permutations.
* **Random selection** - Predicates for randomly selecting and sampling permutations and distinct permutations.

Dedicated `arrangements`, `cartesian_products`, `combinations`,
`derangements`, `multisets`, `partitions`, and `subsequences`
libraries are also available for focused APIs on related operations.
The `arrangements` library is the repetition-allowed counterpart to
this library.


API documentation
-----------------

Open the [../../apis/library_index.html#permutations](../../apis/library_index.html#permutations)
link in a web browser.


Loading
-------

To load all entities in this library, load the `loader.lgt` file:

	| ?- logtalk_load(permutations(loader)).


Testing
-------

To test this library predicates, load the `tester.lgt` file:

	| ?- logtalk_load(permutations(tester)).
