The Camel, 3ed. has an example:

package LuckyDraw;
use overload
    '<>' => sub {
        my $self = shift;
        return splice @$self, rand @$self, 1;
    };
sub new {
    my class = shift;
    return bless [@_] -> $self;
}
1;
[download]

The book does not discuss the rules, but I'm sure this example breaks some of them. To work with while (<$foo>){}, I think the return value should be true in 'bool' context until the source is exhausted. To cope with my @shuffle=<$deck>; and with slices, a wantarray clause should be there to shuffle and return the whole $deck, leaving $deck empty.

The rules you observe should only be the ones you need to observe.

After Compline,
Zaxo