What is a Bool?
Perl allows pretty much any value to be evaluated in a boolean context:
if ($something) {
...
}
No matter what $something
is, it will safely evaluate to either true or false. (With the exceptions of a few edge cases like blessed objects which are overloaded to throw an error when evaluated as booleans.)
So when a Moose class does something like this, what does it mean?
has something => (
is => 'ro',
isa => 'Bool',
);