use Devel::Symdump;
use strict;
use warnings;

use constant   SINS  => qw(pride envy gluttony lust anger greed sloth);

my $dS = Devel::Symdump->new(__PACKAGE__);

local $\="\n";

print " here are some constants (prototype '')";

for my $f( $dS->functions ) {

    my $p = prototype $f;
    print $f if defined $p and $p eq '';
}

__END__
 here are some constants (prototype '')
main::SINS