I have to mention OMeta, a language based on PEGs (plus a few extensions): http://www.tinlizzie.org/ometa/ http://www.tinlizzie.org/ometa/ It's dead simple, an

I have to mention OMeta, a language based on PEGs (plus a few extensions): http://www.tinlizzie.org/ometa/ http://www.tinlizzie.org/ometa/ It's dead simple, and quite powerful: it helps implement all compilation phases, from parsing to code generation. And it compiles itself in about 400 lines of code.