package Allergies;

use strict;
use warnings;

use List::Util 'first';

my @allergens = qw(eggs peanuts shellfish strawberries tomatoes chocolate pollen cats);

sub new {
    my ($class, $score) = @_;
    my $self = bless {} => $class;
    $self->{score} = reverse sprintf "%08b", $score;

    return $self;
}

sub allergic_to {
    my ($self, $allergen) = @_;

    my $index = first { $allergens[$_] eq $allergen } 0..$#allergens;

    return substr $self->{score}, $index, 1; 
}

sub list { [ grep { $_[0]->allergic_to($_) } @allergens ] }

__PACKAGE__;