# `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 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)).