Jonathan Worthington (jnthn). YAPC::Europe 2011 in Riga.
Perl 6 grammars are a powerful way to parse text, and extract structure from it. They take what you already know about regexes and object orientation and bring it together powerfully. It's great, but...what happens when your grammar won't match something you think it should?
In this talk, I'll offer some tips on how to hunt down common problems with grammars, understand what's going wrong and fix it.