Side note: Perl might have booleans now, maybe. :P No idea how compatible or permanent but they’re trying (v36.0).

builtin::true, builtin::false, builtin::is_bool

true and false return boolean true and false values. Perl is still perl, and doesn't have strict typing of booleans, but these values will be known to have been created as booleans. is_bool will tell you whether a value was known to have been created as a boolean.