Hello All, & specially Roberto.
May I suggest a wish for next versions of PPL: always --enable-interfaces=c at least, and possibly --enable-instanciations=c also (so perhaps make that option obsolete). C++ being conceptually a superset of C, I would believe that every PPL client wants at least a C API. (and on todays computers, getting it is cheap in compilation time).
While I understand that not every PPL user is using Ocaml, I would believe that each PPL user has a C compiler (usually, gcc).
FWIW, GCC MELT (see http://gcc.gnu.or/wiki/MELT for more) needs the ppl_io_asprint_Polyhedron and other ppl_io_asprint_ functions from the C API of PPL), and very strangely, depending upon distributions, even with exactly the same version of PPL, this function is available with some distributions and missing in others (it might be related to the libppl-c-dev package of debian, which seems to have died.?).
Alternatively, autoconf tricks (compatible with the autoconf version used by GCC 4.5.1) to test availability of ppl_io_asprint_Polyhedron are welcome. Don't forget Roberto that I am not as fluent with autoconf as you are!
If you read French, more details are available on http://groups.google.com/group/gcc-melt-french/browse_thread/thread/ae128612... (or you can ask them to me, or better yet, try to build GCC MELT).
Cheers.