in reply to
Writing a Programming Language in Perl
BUK's suggestion is quite good. IIRC, it's a fun manuscript.
I've been meaning to suggest Marpa to you for awhile. While still marked experimental it should be excellent for this kind of thing. I've wanted to play with it myself for a long time but tuits being what they are...
Marpa would be used, I'd expect, to convert a language spec/grammar to Perl and then you could use any number of strategies to freeze the resulting code (in memory, file, some other specialized cache) until the original source changed, at which point it could be "recompiled." Doing it this way should afford an easy path for testing and building up a grammar piece by piece. If you don't write tests as you go, you will be sorry down the road. If you do write tests, you'll be able to breeze through wrong turns and accidentally introduced bugs with confidence.