I think the title might be misleading here. It doesn't really transpile Common Lisp to C, it requires you to write in a C-like Lisp dialect so it gets translated to C. Might as well have been an entire Lisp dialect with a compiler of its own.

I think the idea is that you write C-with-sexpr-syntax, but by embedding those s-expressions in Common Lisp, you can make use of macros written in Lisp to generate C code. Essentially, it's a saner preprocessor for C that requires you to write in funky syntax.

I think this would be even more interesting if it could do the C -> s-expression transformation, so that code already written in C could integrate calls to Lisp macros without needing a full rewrite.

A C->S-expression compiler would have to produce very obvious and simple mappings in order for a macro system to be usable. Another way of saying this is that a simple and standard AST would be nice.

https://github.com/vsedach/Vacietis/blob/master/test/reader-...

As-is, C block constructs get mapped directly to Common Lisp special forms like tagbody and prog because those implement a superset of C control flow semantics. Pick different names in vacietis.c and you have an AST.