14,973 research outputs found
Application Software, Domain-Specific Languages, and Language Design Assistants
While application software does the real work, domain-specific languages
(DSLs) are tools to help produce it efficiently, and language design assistants
in turn are meta-tools to help produce DSLs quickly. DSLs are already in wide
use (HTML for web pages, Excel macros for spreadsheet applications, VHDL for
hardware design, ...), but many more will be needed for both new as well as
existing application domains. Language design assistants to help develop them
currently exist only in the basic form of language development systems. After a
quick look at domain-specific languages, and especially their relationship to
application libraries, we survey existing language development systems and give
an outline of future language design assistants.Comment: To be presented at SSGRR 2000, L'Aquila, Ital
Towards Intelligent Databases
This article is a presentation of the objectives and techniques
of deductive databases. The deductive approach to databases aims at extending
with intensional definitions other database paradigms that describe
applications extensionaUy. We first show how constructive specifications can
be expressed with deduction rules, and how normative conditions can be defined
using integrity constraints. We outline the principles of bottom-up and
top-down query answering procedures and present the techniques used for
integrity checking. We then argue that it is often desirable to manage with
a database system not only database applications, but also specifications of
system components. We present such meta-level specifications and discuss
their advantages over conventional approaches
Specializing Interpreters using Offline Partial Deduction
We present the latest version of the Logen partial evaluation system for logic programs. In particular we present new binding-types, and show how they can be used to effectively specialise a wide variety of interpreters.We show how to achieve Jones-optimality in a systematic way for several interpreters. Finally, we present and specialise a non-trivial interpreter for a small functional programming language. Experimental results are also presented, highlighting that the Logen system can be a good basis for generating compilers for high-level languages
Fine-grained Language Composition: A Case Study
Although run-time language composition is common, it normally takes the form
of a crude Foreign Function Interface (FFI). While useful, such compositions
tend to be coarse-grained and slow. In this paper we introduce a novel
fine-grained syntactic composition of PHP and Python which allows users to
embed each language inside the other, including referencing variables across
languages. This composition raises novel design and implementation challenges.
We show that good solutions can be found to the design challenges; and that the
resulting implementation imposes an acceptable performance overhead of, at
most, 2.6x.Comment: 27 pages, 4 tables, 5 figure
Tools for distributed application management
Distributed application management consists of monitoring and controlling an application as it executes in a distributed environment. It encompasses such activities as configuration, initialization, performance monitoring, resource scheduling, and failure response. The Meta system (a collection of tools for constructing distributed application management software) is described. Meta provides the mechanism, while the programmer specifies the policy for application management. The policy is manifested as a control program which is a soft real-time reactive program. The underlying application is instrumented with a variety of built-in and user-defined sensors and actuators. These define the interface between the control program and the application. The control program also has access to a database describing the structure of the application and the characteristics of its environment. Some of the more difficult problems for application management occur when preexisting, nondistributed programs are integrated into a distributed application for which they may not have been intended. Meta allows management functions to be retrofitted to such programs with a minimum of effort
Query Evaluation in Deductive Databases
It is desirable to answer queries posed to deductive databases by computing fixpoints because such computations are directly amenable to set-oriented fact processing. However, the classical fixpoint procedures based on bottom-up processing — the naive and semi-naive methods — are rather primitive and often inefficient. In this article, we rely on bottom-up meta-interpretation for formalizing a new fixpoint procedure that performs a different kind of reasoning: We specify a top-down query answering method, which we call the Backward Fixpoint Procedure. Then, we reconsider query evaluation methods for recursive databases. First, we show that the methods based on rewriting on the one hand, and the methods based on resolution on the other hand, implement the Backward Fixpoint Procedure. Second, we interpret the rewritings of the Alexander and Magic Set methods as specializations of the Backward Fixpoint Procedure. Finally, we argue that such a rewriting is also needed in a database context for implementing efficiently the resolution-based methods. Thus, the methods based on rewriting and the methods based on resolution implement the same top-down evaluation of the original database rules by means of auxiliary rules processed bottom-up
PROLOG META-INTERPRETERS FOR RULE-BASED INFERENCE UNDER UNCERTAINTY
Uncertain facts and inexact rules can be represented and
processed in standard Prolog through meta-interpretation. This
requires the specification of appropriate parsers and belief
calculi. We present a meta-interpreter that takes a rule-based
belief calculus as an external variable. The certainty-factors
calculus and a heuristic Bayesian belief-update model are then
implemented as stand-alone Prolog predicates. These, in turn,
are bound to the meta-interpreter environment through second-order
programming. The resulting system is a powerful
experimental tool which enables inquiry into the impact of
various designs of belief calculi on the external validity of
expert systems. The paper also demonstrates the (well-known)
role of Prolog meta-interpreters in building expert system
shells.Information Systems Working Papers Serie
The Ecce and Logen Partial Evaluators and their Web Interfaces
We present Ecce and Logen, two partial evaluators for Prolog using the online and offline approach respectively. We briefly present the foundations of these tools and discuss various applications. We also present new implementations of these tools, carried out in Ciao Prolog. In addition to a command-line interface new user-friendly web interfaces were developed. These enable non-expert users to specialise logic programs using a web browser, without the need for a local installation
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