We have added another ca. 100 pages to the mbeddr User Guide. In this most recent iteration, we have added tutorials on how to build 8 different language extensions. Each of the tutorials focusses on a different way of extending mbeddr C, or of contributing additional DSLs to the system as a whole. The tutorial project also ships with the full source code for all of these languages, and with example uses.
This latest round of enhancements enables mbeddr users to learn how to add their own abstractions to the mbeddr ecosystem. While we assume some basic familiarity with MPS language definition techniques (which you may acquire from reading the MPS documentation), we do explain things in quite some detail.