43,024 research outputs found
On the Implementation of GNU Prolog
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.Comment: 30 pages, 3 figures, To appear in Theory and Practice of Logic
Programming (TPLP); Keywords: Prolog, logic programming system, GNU, ISO,
WAM, native code compilation, Finite Domain constraint
Experimenting with independent and-parallel prolog using standard prolog
This paper presents an approximation to the study of parallel systems using sequential tools. The Independent And-parallelism in Prolog is an example of parallel processing paradigm in the framework of logic programming, and implementations like <fc-Prolog uncover the potential performance of parallel processing. But this potential can also be explored using only sequential systems. Being the spirit of this paper to show how this can be done with a standard system, only standard Prolog will be used in the implementations included. Such implementations include tests for parallelism in And-Prolog, a correctnesschecking
meta-interpreter of <fc-Prolog and a simulator of parallel execution for <fc-Prolog
Pengines: Web Logic Programming Made Easy
When developing a (web) interface for a deductive database, functionality
required by the client is provided by means of HTTP handlers that wrap the
logical data access predicates. These handlers are responsible for converting
between client and server data representations and typically include options
for paginating results. Designing the web accessible API is difficult because
it is hard to predict the exact requirements of clients. Pengines changes this
picture. The client provides a Prolog program that selects the required data by
accessing the logical API of the server. The pengine infrastructure provides
general mechanisms for converting Prolog data and handling Prolog
non-determinism. The Pengines library is small (2000 lines Prolog, 150 lines
JavaScript). It greatly simplifies defining an AJAX based client for a Prolog
program and provides non-deterministic RPC between Prolog processes as well as
interaction with Prolog engines similar to Paul Tarau's engines. Pengines are
available as a standard package for SWI-Prolog 7.Comment: To appear in Theory and Practice of Logic Programmin
Tabling as a Library with Delimited Control
Tabling is probably the most widely studied extension of Prolog. But despite
its importance and practicality, tabling is not implemented by most Prolog
systems. Existing approaches require substantial changes to the Prolog engine,
which is an investment out of reach of most systems. To enable more widespread
adoption, we present a new implementation of tabling in under 600 lines of
Prolog code. Our lightweight approach relies on delimited control and provides
reasonable performance.Comment: 15 pages. To appear in Theory and Practice of Logic Programming
(TPLP), Proceedings of ICLP 201
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