My own experience with that sort of thing was Lisp calling C through an FFI. In the end, it was too much of a pain and I found a Lisp-only way to do it (it hel

My own experience with that sort of thing was Lisp calling C through an FFI. In the end, it was too much of a pain and I found a Lisp-only way to do it (it helps that SBCL has POSIX system calls available). Debugging was definitely an interesting one. The Lisp debugger was easily confused by problems in the C code (in fact, I cannot think of a time when it was not confused), and running the entire Lisp environment in gdb was just annoying. In the end, when I debugged, I just wound up strategically placing printf calls in the C code and tracing things manually. Of course, this is not a problem of languages, but of tools. What this says is, "When a language includes an FFI, it must also include a good debugger for the FFI." Not necessarily easy, but not impossible by any means. With enough free time, I suspect that the more experienced programmers on HN could produce such tools for any high level language.