s48_extract_string?

Hi --

I'm an old acquaintence of Jonathan's from time spent at MIT. I'm
trying to use Scheme48 for some work where its ability to call C
functions would be useful. I have the latest version (1.8), I've
gotten a minimal print-a-constant-string C function working, but in
attempting the next step -- pass it a Scheme string, extract the
string in C and print it, I find that despite the documentation's
reference to s48_extract_string, that function appears to be missing.
I get

> (load-dynamic-externals "/home/dca/Scheme48/test.so" #f #f #f)

Error: vm-exception
       os-error
       (call-external-value "shared_object_dlopen"
"/home/dca/Scheme48/test.so: undefined symbol: s48_extract_string")

If I substitute a call in the C code to, say, s48_extract_byte_vector,
then load-dynamic-externals is happy.

Suggestions?

Are you still supporting Scheme48 or should I just abandon this and
use something else that may not be as elegant but has current support,
e.g., R?

Thanks --
/Don Allen