TIMTOWTDI

I'm also showing the classic hard-coded approach with nested loops and auto-vivification for comparison.

use strict;
use warnings;
use Data::Dump qw/pp dd/;
use Test::More;



sub matrix (&@){
    my $code = shift;

    my $rec;
    my @coor;
    my $idx;

    $rec = sub  {
        my $level = shift;
        return $code->(@coor) unless @_;

        my $max = shift;
        my $arr = [
                   map {
                       $coor[$level] = $_;
                       $rec->($level+1,@_)
                   } 0 .. $max
                  ];

        return $arr;
    };

    $rec->(0,@_);
}


my $a_matrix = matrix {"<@_>"} 3,2,1;


my @classic;
for my $x (0..3) {
    for my $y (0..2) {
        for my $z (0..1) {
            $classic[$x][$y][$z] = "<$x $y $z>";
        }
    }
}

#pp \@classic;


is_deeply($a_matrix,\@classic,"same matrix");

pp $a_matrix;

done_testing;
[download]

ok 1 - same matrix
[
  [
    ["<0 0 0>", "<0 0 1>"],
    ["<0 1 0>", "<0 1 1>"],
    ["<0 2 0>", "<0 2 1>"],
  ],
  [
    ["<1 0 0>", "<1 0 1>"],
    ["<1 1 0>", "<1 1 1>"],
    ["<1 2 0>", "<1 2 1>"],
  ],
  [
    ["<2 0 0>", "<2 0 1>"],
    ["<2 1 0>", "<2 1 1>"],
    ["<2 2 0>", "<2 2 1>"],
  ],
  [
    ["<3 0 0>", "<3 0 1>"],
    ["<3 1 0>", "<3 1 1>"],
    ["<3 2 0>", "<3 2 1>"],
  ],
]
1..1
[download]

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