[pnathan]

I'm not sure what I mean by a 'dynamic' language. I know it when I see it. ;)

Well, less facetiously: if I can add in-language functions to the image, using the language facilities, while the deployed application is running/paused, I think of that as dynamic.

Data is an interesting thing. There's a crossover point between structured textual data that can be sucked in and when you want to start doing relational queries and stores. Then there's how data is handled in the program. The methods you describe above are very useful, but - insofar as I know of - I think they can be reimplemented without massive grief in other languages, depending on extensibility. Lua has a good reputation for speed; I take it you use it as a standalone?

[silentbicycle]

If being able to update code from a REPL while it's running counts, then yes, though OCaml and Haskell (AFAIK, less experience there) usually involve more edit-compile-reload, to take advantage of the utterly superior compile-time checking. OTOH, Erlang handles "change-in-flight" even better than Lisp does. Of the four, I prefer Erlang, but they're all respectable.

I use Lua both standalone and with C. (Its convenience with linked-in C code won me over from Python, actually.) It's my favorite general purpose language. Nothing against the great performance, but it was a great language before LuaJIT even existed.

Datalog also has a lot of potential as a data format. The industry seems to forget anything invented more than a fortnight ago, though, so it's probably passe until somebody charismatic finally invents it.