items in array A that are not in array B [duplicate]

Answer 1

Not a one liner, but this is likely to be faster than yours on big arrays:

#!/usr/bin/perl
use warnings;
use 5.012;

sub difference {
    my ($first, $second) = @_;
    my %except;
    @except{ @$second } = 1;
    return [ grep { not exists $except{$_} } @$first ];
}

my @anames = ("one", "two", "three", "four", "five");
my @hrefs = ("two", "four", "six");

my $d = difference \@anames, \@hrefs;
say "@$d";