On Tue, Aug 10, 2004 at 12:59:46PM +0100, Simon Marlow wrote:
GHC's use of GMP does cause problems if you want to use GMP for your own purposes, or if you link with external code that wants to use GMP. The real problem is that GMP has internal state, which means it can't be used in a modular way. But there's not much we can do about that.
Possibilities:
- Rename all the symbols in our GMP to be unique. (sounds hard) and ugly
- Replace GMP with something else (someone is working on this, I believe). Do you have a pointer? It sounds interesting. *see below*
- try to get two copies of GMP into your program by pre-linking the RTS with one copy, then linking the rest of the program with the other copy. I'm being intentionally vague here - I feel that this ought to be possible, but it's an ugly hack at best. I'm not sure I share your feelings about that ;) It sounds like symbol-clash-hell. But quite possibly I'm just being ignorant.
- reset GMP's memory allocators before calling it from your code, and set them back to the RTS allocators afterward. Slow, but it should work. It doesn't solve the problem properly though: external libraries which use GMP are still broken. It does indeed seem to work, after a quick test. (new util.c attached)
And it does solve _my_ immediate "problem": I can surround every gmp-operation with a gmp_begin()/gmp_end() and pretend to be happy. (and anyway, I'm just messing around, failure merely means I've got yet another unfinished project ;)) Part of the reason for all this messy FFIing is your post: http://www.haskell.org/pipermail/glasgow-haskell-users/2004-June/006767.html If Integers where implemented via the FFI that would make it quite a bit easier to special-case e.g. (^) and Show for Integer. (IIRC, GMP's mpz-to-string recently got a huge speedup, it would be nice if GHC would automagically profit of that..)
Cheers, Simon
Happy hacking & keep up the good work ;) Remi -- Nobody can be exactly like me. Even I have trouble doing it.