subtype 'FilePath'
    => as 'Str'
    => where { m{^[\w/_.-]{1,80}\z} }
    => message { "I don't trust file name '$_'" };

coerce 'FilePath'
    => from 'Str'
        => via { /(.*)/s; $1 };  # Will be validated soon.

has logfile => (
   is      => 'rw',
   isa     => 'FilePath',
   default => '/var/log/walrus.log',
   coerce  => 1,
);