Perl bounded LRU cache with hash and list

use strict;
use warnings;

sub lru_cache {
    my ($max) = @_;
    my (%map, @order);
    my $touch = sub { my $k = shift; @order = (grep { $_ ne $k } @order, $k) };
    return {
        get => sub { exists $map{$_[0]} ? do { $touch->($_[0]); $map{$_[0]} } : undef },
        set => sub {
            $touch->($_[0]);
            $map{$_[0]} = $_[1];
            delete $map{ shift @order } while @order > $max;
            $_[1];
        },
    };
}

my $c = lru_cache(2);
$c->{set}->(a => 1); $c->{set}->(b => 2); $c->{set}->(c => 3);
print $c->{get}->('a') // 'miss', "\n";