Sorry to the OP for going so far off-topic...

You need to grab a copy of the pugs repository. In that repo you'll find the directory src/perl6/, in which you can find STD.pm and STD5_dump_match.

(If you take somebody else's checkout of the pugs repository please copy the perl6/ folder to your home directory, because you need write accessing for the lex cache).

In that dir, type make, then you can use perl STD5_dump_match $file to print out a match tree.

(You need a perl 5.10.0 in /usr/local/perl to run this, along with a few modules like re::engine::TRE, JSON::XS and Moose. I'll try to install all the dependencies on feather now.)