PEGs are amazing precisely because they're as easy to use as, if not easier than, common regular expression syntax. PEGs are literally the same as regular expre

PEGs are amazing precisely because they're as easy to use as, if not easier than, common regular expression syntax. PEGs are literally the same as regular expressions except 1) alternations are ordered, 2) zero-width assertions are formalized, and 3) quantifiers match greedily. This is effectively the same behavior as the Perl-compatible regular expressions with which most people are familiar. Many PEG engines, especially for dynamic languages, permit grammar composition using first-class variables. That might be a small barrier to people more familiar with the terseness and conceptual simplicity of regular expressions as string'ish values. But it's fairly trivial to implement the latter using PEGs. For example, LPeg provides a small auxiliary module for doing that: http://www.inf.puc-rio.br/~roberto/lpeg/re.html http://www.inf.puc-rio.br/~roberto/lpeg/re.html Also, Rosie seems amazing. I've not yet had the opportunity to make use of it, but I attended a presentation of Rosie by the author at a Lua workshop which left me very impressed.