AoC 2021 day 5, part 2 (Perl)

#!/usr/bin/perl

use utf8;
use strict;
use warnings;
use v5.26;

use List::AllUtils  qw(pairwise all true);
use Math::Utils     qw(sign);

sub vecsum (\@\@) {
    my ($v1,$v2) = @_;
    return (pairwise {$a + $b} @$v1, @$v2);
}

sub veceq (\@\@) {
    my ($v1,$v2) = @_;
    return (all {$v1->[$_] == $v2->[$_]} (0 .. @$v1 - 1));
}

my %grid;
while (<>) {
    my ($x1,$y1,$x2,$y2) = split /\D+/;

    my @Δ = sign($x2 - $x1, $y2 - $y1);
    my @p = ($x1, $y1);
    my @e = vecsum( @{[$x2,$y2]}, @Δ );

    until (veceq( @p, @e )) {
        $grid{$p[0],$p[1]}++;
        @p = vecsum( @p, @Δ );
    }
}

print "Part 2: ", (true {$grid{$_} >= 2} keys %grid), "\n";