Programming Languages: Principles and Paradigms

625 Pages·2007·23.63 MB·English

by  Allen B. Tucker

McGRAW-HILL INTERNATIONAL EDITION

Don't forget to check out the website,
www.mhhe.com/tucker, for additional resources/

* * *

Insti·uctors and sh1dents using Programming Languages: Principles and Paradigms,
Second Edition by Allen B. Tucker and Robert E. Noonan, will tlnd a wide variety of
resources available at the website, www.mhhe.com/tucker.

INSTRUCTOR RESOURCES

Instmctors can access the following resources by contacting their McGraw-Hill Rep-
resentative for a secure password.
·

PowerPoint slides. Contain figures from the book along with lecture notes.
Solutions Manual. Password-protected solutions are provided.
PageOut. A free tool that helps you create your own course website.

STUDENT RESOURCES

The student resources are available to those students using the book. Once you have
accessed the website, you'll see "Student Resources" listed. This section of the site has
a wealth of materials to help you review the various aspects of programming languages.
Inc1uded are:

• Chapter Summaries. Quick summaries provide an essential review of major
ideas and concepts covered in each chapter.

• Glossary. Defines key terms presented in the book.
PowerPoint slides. Contain helpful lecture notes to review important points.
Web linl<s. Connect students to additional resources available online.
Downloadable programs. The programs from the book are downloadable in
multiple languages: C, Ada, Perl, Java, Smalltalk, Python, Scheme, Haskell,
Prolog, etc.
Downloadable Clite interpreter software. Can use for many of the hands-on
exercises.

r
I

es

Principles and Paradigms

Allen B. Tucker

Bowdoin College

Robert E. Noonan
College of William and Mary

Boston
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PROGRAMMING LANGUAGES: PRINCIPLES AND PARADIGMS, SECOND EDITION
International Edition 2007

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To Maida.

Allen Tucker

To Debbie and Paul.
Robert Noonan

Preface

The study of programming languages has evolved rapidly since we began developing
the first edition of this book in 1999. For instance, Java has become the dominant lan-
guage in computer science curricula, beginning with CS 1. Agile progra:mming has
emerged as a coherent approach to software design, and its language preferences are
different from those of traditional programming. The use of formal methods in software
design has begun to creep into the mainstream, and its importance is now significant.
In response to these and other recent events, this edition hopes to capture the
excitement and new challenges that accompany the design of today's and tomorrow's
programming languages. For instance, this edition has a broader and deeper coverage
of all four programming paradigms and the languages that accompany them.

Language Coverage

Paradigm
First Edition
This Edition
Imperative
c
(Chapter 12)
Ada
Perl

Object-Oriented
Java
Java
(Chapter 13)
Small talk
Python

Functional
Scheme
Scheme
(Chapter 14)
Haskell
Haskell
Logic
Pro log
Pro log
(Chapter 15)

The second major change in this edition is that the discussion of language design
principles in the early chapters (2-11) has been greatly expanded. We have added new
examples from contemporary languages (like Python and Perl), using an informal
style of presentation. Moreover, we have eliminated most coverage of older languages
that are no longer in widespread use (such as Pascal and Modula).
The core principles of programming languages-syntax, names, types, semantics,
and functions-are the subjects of Chapters 2, 4, 5, 7, and 9, respectively. These chap-
ters provide a hands-on study of those principles using a broader and deeper selection
of languages and examples than the first edition.
Readers who prefer an implementation-based treatment of syntax, type systems,
semantics, functions, and memory management will find this material in the companion
Chapters 3, 6, 8, 10, and 11. These chapters can be used selectively to enrich the core
principles with which they are related. For example, the study of syntax in Chapter 2

vii

viii
Preface

can be enriched by studying the lexical and syntactic phases of a compiler in Chapter
3. We emphasize that any or all of these companion chapters may be skipped, espe-
cially in a first course on programming languages.
Three companion chapters include optional sections with more formal mathemat-
ical treatments. These optional sections are marked with the same marginal graphic as
this paragraph to indicate that they are optionaL Appendix B provides a review of the
key discrete mathematics topics and notations underlying these sections for students
who need a quick refresher.
Finally, the special topics chapters (16, 17, and 18) provide detailed introductions
to the study of event-handling, concurrency, and program conectness. The first edi-
tion had covered two of these (event-handling and concurrency), but the chapter on
correctness is new to this edition.
Overall, this new edition contains a broad and deep coverage of the plinciples,

paradigms, and special topics in programming languages. The book now has 18 chapters.
Since individual instructors have different views on what should be emphasized in a
programming languages course, this book provides a variety of options.

EMPHASIS

This text emphasizes a thorough, hands-on treatment of the key issues in programming
language design. It provides instructors and students with a mixture of explanatory-
based and implementation-based experiences. The implementation-based experiences
includes hands-on experimentation with the design and implementation of a modest
subset of C, called Clite, which is fully defined in Appendix A for easy reference.
As noted above, this edition has an expanded treatment of the major program-
ming paradigms. We believe that to master a paradigm, students must actively use that
paradigm to solve a programming problem. If, for example, your students have no
experience with functional programming, we recommend that they learn enough
Scheme or Haskell to complete a reasonable programming project. To paraphrase one
reviewer's comments:

To understand a paradigm you must become the paradigm.

If, on the other hand, your introductory, discrete mathematics, or AI course already
includes functional programming, you might choose to skip this chapter and empha-
size another paradigm or special topic instead.

COURSE ORGANIZATION

Figure 1 shows how the text divides into three major sections:

Principles
Paradigms
Special Topics

Tn the first section, Chapters 2, 4, 5, 7, and 9 cover five core principles-Syntax,
Names, Types, Semantics, and Functions. Parts of the remaining chapters (3, 6, 8, 10,
and 1 1) in this section can be added to provide a deeper level of topic coverage. On

Chapter

Introduction

Syntactic
Analysis
3

Type
Systems

6

Semantic
Interpretation
8

Pre far

Function
Interpretation

10

2 L
4 ~
5 L
7 L
9 L
11

Syntax
Names
Types
Semantics

the Principles
\
the Paradigms

(

16

the Special Topics
17

18

Event-Handling

Concurrency

Conectness

Functions
Memory
Management

12
Imperative Programming

13
Object-Oriented Programming

14
Functional Programming

15
Logic Programming

I Figure 1 Content dependencies among the chapters.

the other hand, advanced or graduate courses may include several of these topics,
while de-emphasizing material in the later chapters.
The second section of the text covers the four major programming paradigms:

Imperative programming
Object-oriented programming
Functional programming
Logic programming

These chapters are relatively independent of each other and can be studied in any
order. However, a one~semester course will normally include one or two of these
chapters, in addition to the principles. The choice of paradigms, of course, may vary
with the preferences of the instructor and the content of other courses in the cunicu-
lum. For instance, if the cuniculum regularly offers a course in object-oriented
design, Chapter 13 can be skipped.
Chapter 12 is completely new to this edition; it demonstrates the key features of
imperative programming in each of three different languages: C, Ada, and Perl. C was
chosen because it illustrates the problems caused by weak typing. In contrast, Ada is

I "

X
~· Preface

strongly typed, thus providing an interesting compadson with C. Finally, Perl was
chosen because it illustrates a dynamically typed scripting language. For instructors
who include Chapter 12, we recommend that at least one language unfamiliar to stu-
dents be covered in enough depth to assign an interesting programming project.
Chapter 13 has undergone a major rewrite from the first edition. Now, the fea-
tures of an object-oriented language are explored using Java, Smalltalk, and Python.
Sma11talk is included because of its simplicity, Java because of its dominance, and
Python because of its agility in scripting applications. Students who have had an
introductory sequence in Java, but no course in object-oriented design and program-
ming, may benefit from learning one of the other two languages. The object-oriented
paradigm will continue to be important in the future.
The functional and logic programming paradigms (Chapters 14 and 15) continue
to be distinctive in their applications and respective programming styles. Our treat-
ment of functional programming includes parallel Scheme and Haskell discussions, so
that students can master the ideas of functional programming by studying either lan-
guage and omitting the other.
The third section of the text covers three special topics:

• Event-handling
• Concurrency
• Correctness

An undergraduate programming languages course will normally not have time to
cover more than one of these topics. The fact that some of these topics appear else-
where in the cuniculum can help instructors decide which one(s) to include in the
programming languages course.
Chapters 16 and 17, Event-Handling and Concurrency, represent unusual control
issues that can be well-treated in a study of programming languages. Both are seeing
increasing visibility in programming applications, especially in scientific computing
and embedded systems. Key topics that students need to cover in these areas include
communication, deadlocks, message passing, nondetenninism, event-handling, inter-
process communication, and a sampling of the many and varied applications (e.g.,
operating systems, GUI interactions, and home alarm systems) in which these topics
regularly appear.
Finally, we are excited about the new Chapter 18 on Correctness, which discusses
recent developments in programming language support for formal methods. For exam-
ple, the developers of Spark Ada report 100 times fewer bugs with 3-5 times higher
productivity rates using a technique called correctness by construction [Barnes, 2003].
Because we believe that the support for more formal approaches to software design
will be increasingly important to programming languages in the future (much like
object-oriented programming is very important now), we hope that instmctors will
consider including this chapter in their programming languages courses.
Chapter 18 begins with a review of axiomatic semantics [Hoare, 1969] and its
use in the verification of imperative programs. It expands this theory by covering the
concept of design by contract [Meyer, 1988] in object-oriented languages, and its
application using the Java Modeling Language (JML). This chapter also covers the

Preface
xi

concept of structural induction and its use to prove the correctness of functional
programs.
It can be argued that some of the topics in the latter chapters belong in other
courses, rather than in a study of programming languages and paradigms. For example,
the study of concurrency, event-driven programming, and program correctness can each
be viewed as a separate course. Moreover, much of the material in Chapters 3, 6, 8, 10,
and 11 can·be viewed as the basis for a separate compiler course. Because many under-
graduate programs do not offer such separate courses in these topics, this text provides
an opportunity to introduce them in the setting of a programming languages course.

PREREQUISITES AND OTHER GUIDANCE

Students entering this course should have completed at least an introductory course
and a data structures course. In the data structures course, students should have
become familiar with linked lists, stacks, flexible arrays, and hash tables.
Moreover, knowledge of Java is a prerequisite if the course includes any of the
following implementation-oriented chapters: 3, 6, 8, 16, and 17. Without knowledge
of Java, students should have experience with C, C++, or C# from their data struc-
tures course.
We recommend that students also have access to a good Java tutorial, reference
manual, and programming environment. Such tutorials and references are readily
available on the Web (see, for example, http://java.sun.com/docs!books/tutorial/).
Some of our discussions depend strictly on features that have been introduced in Java
1.4 and 1.5. These features are clearly noted in the text.
We also hope that students will have some modest mathematical skills, as would
be found in an elementary discrete mathematics or discrete structures course. While
this is not a strict prerequisite, it is essential for students who engage the mathemati-
cally miented sections in some of the chapters (3, 6, 8, 10, and 18). A review of the
basic ideas of functions, sets, logic, and proof is provided in Appendix B.
This text is consistent with the recommendations of Computing Curricula 2001
[CC2001, 2001]. It also covers all the topics in the Programming Languages course
described in the Liberal Arts Model Curriculum [Walker and Schneider, 1996J, and its
newer 2005 draft version (www.lacs.edu).
With regard to Computing Curricula 2001, the material in this text covers all of
the topics (PLJ through PL11) in the Programming Languages section of the core
body of knowledge. It also covers other topics in that core body of knowledge, such as
event-dliven and concurrent programming (PF6), memory management (OSS), func-
tional and logic programming (IS), and software engineeling (SE). This text treats
each topic in greater depth than that suggested by Computing Curricula 2001.

LANGUAGE RESOURCES AND WEBSITE

The software for this text can be used with any implementation of Java 1.5 or higher. We
have implemented the Java software for this book using Sun's Java 1.5. Here is a list of
Web-based sources that we recommend for tutorial and other information on the
major languages covered in this book.

xii
Preface

Language
Web Source

Ada
gnu.org
C,C++
gnu.org
Haskell
haskell.org
Java 1.5
java.sun.com

Perl
perl.com

Prolog
swi-prolog.org

Python
python.org
Scheme
drscheme.org
Small talk
squeak.org

A suite of software and other support to accompany this text is available at the
website www.mhhe.com/tucker. It contains the following materials:

• A complete Java implementation of the syntax, type system, and semantics of
Clite.

• A downloadable set of all the runnable programs discussed in this text.
A set of PowerPoint slides to support course lectures.
Answers to the exercises (available to instructors via a secure password).

Acknowledgments

Many persons have helped guide us in the development of this text. James Lu was a
key collaborator in the early conceptualization of the first edition. Bill Bynum at the
College of William and Mary and Laurie King at the College of the Holy Cross con-
tributed to Chapters 4 and 8, respectively. David Coppit at William and Mary intro-
duced us to the use of proof trees, which appear in Chapter 18. Students at Bowdoin
and William and Mary contributed to the first edition and early versions of this edi-
tion. Notably, Doug Vail developed solutions to some of the more challenging prob-
lems. Wyatt Dumas helped rewrite the software for the second edition and made sig-
nificant contributions to the content of two chapters.We thank all of our reviewers:

Phil Ventura
Aaron Keen

John Donald
Tia Watts
Ron Olsson
Thomas D. Rethard
Alex Thornton
Gerald Baumgartner
Ken Slonneger
David R. Falconer
TaeW. Ryu

University of Buffalo, SUNY
California Polytechnic State University,

San Luis Obispo

San Diego State University
Sonoma State University
University of California, Davis
University of Texas, Arlington
University of California, Irvine
Ohio State University
University of Iowa
California State University, Fullerton
California State University, Fullerton

Qi Cheng
Rainey Little
Jay-Evan J. Tevis
John Hannan
Neelarn Soundarajan
Robert van Engelen
Shannon Tauro
Gloria Melara
Amer Diwan
Susan Gauch
Henri Casanova
Cristina V. Lopes
Salih Yurttas
Roman W. Swiniarksi
Arnar Rahej a
Franck Xia
Rajendra K. Raj
Randall D. Beer
Robert M. Cubert
Liang Cheng
David Hemmendinger

University of Oklahoma
Mississippi State University
Auburn University
Pennsylvania State University
Ohio State University
Florida State University
University of California, Irvine

Cal~'fomia State University, Northridge
University of Colorado, Boulder
University of Kansas
University of California, San Diego
University of California, Irvine
Texas A&M University
San Diego State University

Preface
xiii

Cal{fomia State Polytechnic University, Pomona
University of Missouri, Rolla
Rochester Institute of Technology
Case Western Reserve University
University of Florida
Lehigh University
Union College

for their careful reading and constructive comments throughout the development of
the first and second editions of this text, which are greatly improved by their collec-
tive insight. The authors offer a special thanks to David Hemmendinger of Union Col-
lege for his careful editing and extensive suggestions, most of which have been incor-
porated into this edition.
Finally, we would like to thank our editors, Rebecca Olson and Alan Apt, for
their vision, guidance, and support. They have guided the development of the second
edition with extraordinary skill.

Allen B. Thcker
Bowdoin College
Robert E. Noonan
College of William and Mary

Brief Contents

Overview

2
Syntax
23

3
lexical and Syntactic Analysis
57

4
Names
85

5
Types
101

6
Type Systems
135

7
Semantics
153

8
Semantic Interpretation
197

9
Functions
225

10
Function Implementation
243

11
Memory Management
263

12
Imperative Programming
277

13
Object-Oriented Programming
309

14
Functional Programming
361

15
logic Programming
413

16
Event-Driven Programming
447

17
Concurrent Programming
483

18
Program Correctness
519

XV

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