Dear Monks

What is the easiest way to constrain the keys of a HashRef in Moose?

I have been looking through the various type constraint modules in Moose (for the first time!) and am feeling a little overwhelmed.

I initially thought of something on the lines of 

#!/usr/bin/perl

package Test::HashK;

use Moose;
use Moose::Util::TypeConstraints;

enum 'colors', [qw(red green blue)];
has scores => ( is => 'rw', isa => 'HashRef[colors]', default => sub{{
+}} ); # I want the allowed *keys* to be colors

1;

[download]
but then if I run the following script: 
#!/usr/bin/perl

use strict;

use Test::HashK;

my $hk=Test::HashK->new;

$hk->scores->{'red'} = 53;
$hk->scores->{'black'} = 100;
$hk->scores->{1} = 'blue';
$hk->scores->{2} = 'dinosaur';

[download]

it runs through to completion without any problem, thus not appearing to contrain either the keys or the values

Obviously I have no idea what I am doing! Any thoughts?

In reply to constraining the keys of a HashRef in Moose by tomgracey

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