I have just uploaded a package that implements a language on top of TCL. I was originally planning to use it for implementing persistence in OpenACS but the time has passed. The actual code does not exceed 500 lines including the DTD and the comments (less than 400 lines without the comments). Resulting spec can be validated with the DTD in the code using xmlint (did that already - just in a hurry to get some other work done right now).
I also plan to rewrite all of my other apps/packages on top of it. The resulting spec (tclsh read-nest.tcl message.nest) can be compiled into C code (while retaining the ability to function in TCL) just like I did with the templating more than a year ago.
You can find the "nest" package here:
http://www.openacs.org/file/4205606/nest.tar.bz2.bz2
You may find my templating presentation in EuroTCL 2013 relevant:
http://www.tcl.tk/community/tcl2013/EuroTcl/presentations/EuroTcl2013-Demetriou-WebTemplating.pdf
