[jdoege]

Packrat parsing is not an intrinsic aspect of PEG, nor does it increase memory usage. Further, the memory issue is more academic than real. If you are having memory issues, you will add intentional pruning to your parser to purge anything that comes before a point behind which you can not backtrack. Such points tend to exist in most computer languages. Yes, this is not a strict part of PEG but being academically pure when constructing a parser of any complexity leads to a short trip to madness. Perl 6's grammar construct is not pure to the PEG definition but it is a recursive descent grammar engine with all the bells and whistle you could want including functional components such as argument pattern matching which makes generic and reusable grammar expression a cinch.

Also, PEG makes having a context sensitive lexer not simply trivial but no effort at all because lexing and parsing are all the same process. It you want to have two different token-types for an INT-looking-thing at two different places in your grammar for, "reasons", you are free to do so. Try that in a discrete lex/parse style grammar.