Lieven De Keyzer wrote:
> I'm trying to build lang/swi-prolog-lite. During the configuration
> phase I receive this message:
> 
> ****************************************************************
> * Could not find libgmp or gmp.h.  GMP enables SWI-Prolog
> * support for unbounded integer arithmetic and rational numbers.
> *
> * See README.gmp for details.
> ****************************************************************.
> 
> However, I have installed devel/gmp.

Try adding the following line to lang/swi-prolog-lite/Makefile:

.include "../../devel/gmp/buildlink3.mk"

-- 
Christian