Hi there, I may well be missing something, but it seems the life of people interfacing C/C++ and Prolog programs on MacOS would be simplified if SWI-Prolog.h and the other interface header file could be installed in some fixed place, such as /opt/local/include, as well as in /opt/local/lib/swipl-x.y.zz/include. This would match what happens on, e.g., the Linux version where these header files are installed in, say, /usr/local/include as well as in /usr/local/lib/swipl-x.y.zz/include. Please note that I know _nothing_ about MacOS: I am only trying to support users of the Parma Polyhedra Library, yet minimizing the number of special cases I have to take into account. All the best, Roberto P.S. BTW, why /opt/local instead of /usr/local? -- Prof. Roberto Bagnara Computer Science Group Department of Mathematics, University of Parma, Italy http://www.cs.unipr.it/~bagnara/ mailto:bagnara@cs.unipr.it