The GNU Prolog system and its implementation

Journal of Functional and Logic Programming, 2001

In this paper we describe the design and the implementation of the GNU Prolog system. This system draws on our previous experience of compiling Prolog to C in the wamcc system and of compiling finite domain constraints in the clp(FD) system. The compilation scheme has however been redesigned in order to overcome the drawbacks of compiling to C. In particular, GNU-Prolog is based on a low-level mini-assembly platform-independent language that makes it possible to avoid compiling C code, and thus drastically reduces compilation time. It also makes it possible to produce small stand-alone executable files as the result of the compilation process. Interestingly, GNU Prolog is now compliant to the ISO standard, includes several extensions (OS interface, sockets, global variables, etc) and integrates a powerful constraint solver over finite domains. The system is efficient and in terms of performance is comparable with commercial systems for both the Prolog and constraint aspects.

2010

GNU Prolog is a general-purpose implementation of the Prolog language, which distinguishes itself from most other systems by being, above all else, a native-code compiler which produces standalone executables which don't rely on any byte-code emulator or meta-interpreter. Other aspects which stand out include the explicit organization of the Prolog system as a multipass compiler, where intermediate representations are materialized, in Unix compiler tradition. GNU Prolog also includes an extensible and high-performance finite domain constraint solver, integrated with the Prolog language but implemented using independent lower-level mechanisms. This article discusses the main issues involved in designing and implementing GNU Prolog: requirements, system organization, performance and portability issues as well as its position with respect to other Prolog system implementations and the ISO standardization initiative.