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PRINCIPLES OF programming WITH COMPLEX OBJECTS AND COLLECTION TYPES

THEORETICAL COMPUTER SCIENCE 1995年第1期149卷 3-48页

作者： BUNEMAN, P NAQVI, S TANNEN, V WONG, LS BELLCORE MORRISTOWN NJ 07960 USA INST SYST SCI SINGAPORE 0511 SINGAPORE

We present a new principle for the development of database query languages that the primitive operations should be organized around types. Viewing a relational database as consisting of sets of records, this principle dictates that we should investigate separately operations for records and sets. There are two immediate advantages of this approach, which is partly inspired by basic ideas from category theory. First, it provides a language for structures in which record and set types may be freely combined: nested relations or complex objects. Second, the fundamental operations for sets are closely related to those for other ''collection types'' such as bags or lists, and this suggests how database languages may be uniformly extended to these new types. The most general operation on sets, that of structural recursion, is one in which not all programs are well-defined. In looking for limited forms of this operation that always give rise to well-defined operations, we find a number of close connections with existing database languages, notably those developed for complex objects. Moreover, even though the general paradigm of structural recursion is shown to be no more expressive than one of the existing languages for complex objects, it possesses certain properties of uniformity that make it a better candidate for an efficient, practical language. Thus rather than developing query languages by extending, for example, relational calculus, we advocate a very powerful paradigm in which a number of well-known languages are to be found as natural sublanguages.

关键词： programming theory

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Explaining type inference

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SCIENCE OF COMPUTER programming 1996年第1期27卷 37-83页

作者： Duggan, D Bent, F Department of Computer Science University of Waterloo Waterloo Ontario Canada N2L 3G1

Type inference is the compile-time process of reconstructing missing type information in a program based on the usage of its variables. ML and Haskell are two languages where this aspect of compilation has enjoyed some popularity, allowing type information to be omitted while static type checking is still performed. Type inference may be expected to have some application in the prototyping and scripting languages which are becoming increasingly popular. A difficulty with type inference is the confusing and sometimes counter-intuitive diagnostics produced by the type checker as a result of type errors. A modification of the unification algorithm used in Hindley-Milner type inference is presented, which allows the specific reasoning which led to a program variable having a particular type to be recorded for type explanation. This approach is close to the intuitive process used in practice for debugging type errors. The algorithm is practical, and has been implemented in the Standard ML of New Jersey compiler. The modified unification algorithm also appears useful in other domains, including logic program debuggers and semantics-based programming environments.

关键词： programming theory

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An operational semantics of sharing in lazy evaluation

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SCIENCE OF COMPUTER programming 1996年第3期27卷 289-322页

作者： Seaman, J Iyer, SP N CAROLINA STATE UNIV DEPT COMP SCIRALEIGHNC 27695

From a theoretical point of view, lazy evaluation corresponds to the call-by-name evaluation method, which substitutes arguments for parameters before evaluating them and never evaluates under a lambda. From an implementation perspective, lazy evaluation is often equated with the call-by-need method, which is similar to call-by-name except that arguments are shared. When an argument's value is required, it is evaluated and its result is stored and used for any other reference to it. The theoretical version of lazy evaluation, or call-by-name, is easily formalized with the reduction rules of lambda calculus. However, it has proven rather difficult to formalize the rules of lazy evaluation with sharing, or call-by-need, in such a way that it both captures sharing and is useful for reasoning. Many optimizations are based on analyses of program behavior which are dependent on whether arguments are implemented via sharing or not. Thus, it is important to have such a model of lazy evaluation in order to develop correct analyses. In this paper, an operational semantics of PCF is presented which captures the sharing inherent in the call-by-need implementation of lazy evaluation in a form that is suitable for reasoning. The semantics uses explicit substitutions to implement sharing. The link between the theoretical and implementation versions of lazy evaluation is made by showing the correctness of the call-by-need semantics with respect to a standard call-by-name semantics for PCF.

关键词： programming theory

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On termination and confluence properties of disjoint and constructor-sharing conditional rewrite systems

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THEORETICAL COMPUTER SCIENCE 1996年第1期165卷 97-131页

作者： Gramlich, B Fachbereich Informatik Universität Kaiserslautern Postfach 3049 D-67653 Kaiserslautern Germany

We investigate the modularity behavior of termination and confluence properties of (join) conditional term rewriting systems. We give counterexamples showing that the properties weak termination, weak innermost termination and (strong) innermost termination are not preserved in general under signature extensions. Then we develop sufficient conditions for the preservation of these properties under signature extensions, and more generally, for their modularity in the disjoint union case. This leads to new criteria for modularity of termination and completeness generalizing known results for unconditional systems. Finally, combining our analysis with recent related results on the preservation of semi-completeness, we show how to cover the (non-disjoint) case of combined conditional rewrite systems with shared constructors too.

关键词： programming theory

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ON THE MATHEMATICS OF SEQUENTIAL DECOMPOSITIONS

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SCIENCE OF COMPUTER programming 1993年第3期20卷 253-289页

作者： DESHARNAIS, J MILI, A MILI, F UNIV LAVAL DEPT INFORMATQUEBEC CITY G1K 7P4QUEBECCANADA UNIV OTTAWA DEPT COMP SCIOTTAWA K1N 6N5ONTARIOCANADA OAKLAND UNIV SCH ENGN & COMP SCIROCHESTERMI 48309

We view the process of constructing a program as the stepwise transformation of a relation into simpler relations. In this paper, we focus on a particular transformation: that which decomposes the specification of an iterative program into the specification of the initialization segment and the specification of the while loop. We investigate in some detail the mathematics of this decomposition.

关键词： programming theory

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AN ANALYSIS OF SEVERAL SOFTWARE DEFECT MODELS

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IEEE TRANSACTIONS ON SOFTWARE ENGINEERING 1988年第9期14卷 1261-1270页

作者： YU, TJ SHEN, VY DUNSMORE, HE MICROELECTRON & COMP TECHNOL CORP AUSTINTX 78759 PURDUE UNIV DEPT COMP SCIW LAFAYETTEIN 47907

Results are presented of an analysis of several defect models using data collected from two large commercial projects. Traditional models typically use either program matrices (i.e. measurements from software products) or testing time or combinations of these as independent variables. The limitations of such models have been well-documented. The models considered use the number of defects detected in the earlier phases of the development process as the independent variable. This number can be used to predict the number of defects to be detected later, even in modified software products. A strong correlation between the number of earlier defects and that of later ones was found. Using this relationship, a mathematical model was derived which may be used to estimate the number of defects remaining in software. This defect model may also be used to guide software developers in evaluating the effectiveness of the software development and testing processes.

关键词： programming theory Software Reliability Software Testing Software Reliability Software Defect Models Mathematical Model Software Development Software Testing Mathematical Model Software Measurement Predictive Models Time Measurement Phase Detection programming Software Metrics Resource Management Microelectronics

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COMBINED USE OF FINITE-STATE MACHINES AND PETRI NETS FOR MODELING COMMUNICATING PROCESSES

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ELECTRONICS LETTERS 1984年第22期20卷 915-916页

作者： PATTAVINA, A TRIGILA, S FDN UGO BORDONI I-00153 ROMEITALY

In order to model and verify systems of concurrent processes (such as those involved in communication protocols), finite-state machines and Petri nets can be used as local and global models, respectively. The problem of composing a set of communicating finite-state machines into a single global Petri net is considered in the letter with special attention to the case of more than two processes.

关键词： communicating sequential processes finite-state machines concurrent processes Combinatorial mathematics Automata theory graph theory Petri nets communicating processes local models global models programming and algorithm theory programming theory finite automata modelling communication protocols parallel processing

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Introduction to the special issue "Best of Empirical Studies of Programmers 7"

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INTERNATIONAL JOURNAL OF HUMAN-COMPUTER STUDIES 1999年第1期51卷 3-5页

作者： Wiedenbeck, S Scholtz, J Dalhousie Univ Fac Comp Sci Halifax NS B3J 2X4 Canada Natl Inst Stand & Technol Gaithersburg MD 20899 USA

The paper `Best of Empirical Studies of Programmers 7', from the Seventh Workshop on Empirical Studies of Programmers held in 1997 was initiated to bring a group of high-quality papers, representing a range of issues in the cognition of programming to a wide audience. Four papers are contained in this special issue. They treat a wide range of themes in the cognition of programming and, thus, give some sense of the scope of the field.

关键词： programming theory

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What are race conditions? Some issues and formalizations

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ACM letters on programming languages and systems 1992年第1期1卷 74-88页

作者： Netzer, Robert H.B. Miller, Barton P. Univ of Wisconsin Madison United States

In shared-memory parallel programs that use explicit synchronization, race conditions result when accesses to shared memory are not properly synchronized. Race conditions are often considered to be manifestations of bugs, since their presence can cause the program to behave unexpectedly. Unfortunately, there has been little agreement in the literature as to precisely what constitutes a race condition. Two different notions have been implicitly considered: one pertaining to programs intended to be deterministic (which we call general races) and the other to nondeterministic programs containing critical sections (which we call data races). However, the differences between general races and data races have not yet been recognized. This paper examines these differences by characterizing races using a formal model and exploring their properties. We show that two variations of each type of race exist: feasible general races and data races capture the intuitive notions desired for debugging and apparent races capture less accurate notions implicitly assumed by most dynamic race detection methods. We also show that locating feasible races is an NP-hard problem, implying that only the apparent races, which are approximations to feasible races, can be detected in practice. The complexity of dynamically locating apparent races depends on the type of synchronization used by the program. Apparent races can be exhaustively located efficiently only for weak types of synchronization that are incapable of implementing mutual exclusion. This result has important implications since we argue that debugging general races requires exhaustive race detection and is inherently harder than debugging data races (which requires only partial race detection). Programs containing data races can therefore be efficiently debugged by locating certain easily identifiable races. In contrast, programs containing general races require more complex debugging techniques.

关键词： programming theory

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COMPOSITION-NOMINATIVE ASPECTS OF ADDRESS programming

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CYBERNETICS AND SYSTEMS ANALYSIS 2009年第6期45卷 864-874页

作者： Nikitchenko, M. S. Taras Shevchenko Natl Univ Kiev Ukraine

Basic principles of address programming, namely, addressness and program control are considered and analyzed. Their further development within the framework of composition and compositionnominative programming is demo... 详细信息

关键词： programming theory address programming composition programming composition-nominative programming principle of addressness principle of program control program semantics composition data structure nominative data

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