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Author image Chernenko Dmitriy


List::Helpers::XS - Perl extension to provide some usefull functions with arrays


  use List::Helpers::XS qw/ :shuffle :slice /;

  my $slice = random_slice(\@list, $size); # returns array reference, @list is partitial shuffled

  random_slice(\@list, $size); # @list is now truncated and shuffled


  # undef value will be skipped
  shuffle_multi(\@list1, \@list2, undef, \@list3);

  # the same for tied arrays

  tie(@list, "MyPackage");
  my $slice = random_slice(\@list, $size); # returns array reference


This module provides some rare but usefull functions to work with arrays. It supports tied arrays.


This method receives the array and the amount of required elements to be shuffled, shuffles array's elements and returns the array reference to the new arrays with num elements from original one.

If num is equal or higher than amount of elements in array, then it won't do any work.

It doesn't shuffle the whole array, it shuffles only num elements and returns only them. So, if you need to shuffle and get back only a part of array, then this method can be faster than others approaches.

Be aware that the original array will be shuffled too, but it won't be sliced.

In void context the original list will be truncated and shuffled.


Shuffles the provided array. Doesn't return anything.


Shuffles multiple arrays. Each array must be passed as array reference. All undefined arrays will be skipped. This method will allow you to save some time by getting rid of extra calls. You can pass so many arguments as Perl stack allows.


Benchmarks of random_slice method in comparison with List::MoreUtils::samples and List::Util::sample showed that current version of random_slice is very similar to the first ones in some cases. But in case of huge amount of iterations it starts to slow down due to some performance degradation.

So, the usage of List::MoreUtils::samples (it's the fastest now) and List::Util::sample is more preferable. I'll keep random_slice for backward compatibility.

The benchmark results for shuffle method

                            shuffle_huge_array  List::Helpers::XS::shuffle
shuffle_huge_array                          --                         -5%
List::Helpers::XS::shuffle                  5%                          --

                            shuffle_array  List::Helpers::XS::shuffle
shuffle_array                                      --             -4%
List::Helpers::XS::shuffle                          4%             --

                            List::Util::shuffle  List::Helpers::XS::shuffle
List::Util::shuffle                          --                        -63%
List::Helpers::XS::shuffle                  170%                         --


Chernenko Dmitriy, cdn@cpan.org


Copyright (C) 2021 by Dmitriy

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.26.1 or, at your option, any later version of Perl 5 you may have available.