At my company, we have a DSL to represent a data flow network. I'm looking into ways to make this environment more debuggable (not only native C++, since that would throw you out of the domain view).
Are there existing debugger 'frontends' that I can write an adapter for to e.g. break data flow, step forward one node, investigate edge contents, ...?
You might find this paper on debuggers for DSLs useful: http://gray.cs.ua.edu/pubs/ldta-2007.pdf
In general, a good way to do this is to modify the DSL code generator to produce most of the debugger infrastructure necessary (for "debug" compiles).