Your post made me pretty much enthusiastic about Pugs, so I also gave it a try. Nice to see some Perl6 in work...

Although, neither I had luck with multiple dispatch. It seems to be broken in the current svn tree. What makes me think this is that I tried some of the sample codes at the FeatherweightPerl6 website to make work, but to no avail. I tend to get similar errors like you...