An Introduction To Programming With Specifications

Providing a thorough treatment of most elementary programme development techniques, this revised edition covers topics such as procedures, parameters, recursion and data refinement, with the integration of specification, development and coding, based on ordinary (classical) logic. This second edition features: substantial restructuring of earlier material, streamlining the introduction of programming language features; simplified presentation of procedures, parameters and recursion; an expanded chapter on data refinement, giving the much simpler laws that specialize to functional abstractions; a new chapter on recursive types (trees etc) and appropriate control structures; and, following the original concluding case study, two completely new ones: "the recursive treatment of the largest rectangle under a histogram", and a specification and extended developnent of an electronic mail system (including limited concurrency).

A feature of modern advanced computing is the functional approach to programming. In this book, the authors present an introduction to the mathematics which underline functional programming, emphasizing the understanding of definition and specification--a prerequisite of good programming and problem solving with a computer. The book is self-contained, requiring a low level of mathematical sophistication and may be used as an introduction to the mathematics of programming. Provides an introduction to the functional approach to programming**Emphasizes the problem to be solved, not the programming language**Takes the view that all computer programs are a definition of a function**Includes exercises for each chapter**Can be used as a pre-programming language introduction to the mathematics of computing.

Topics • what this book is about, • its intended audience, • what the reader ought to know, • how the book is organized, • acknowledgements. Specifications express information about a program that is not normally part of the program, and often cannot be expressed in a programming lan guage. In the past, the word "specification" has sometimes been used to refer to somewhat vague documentation written in English. But today it indicates a precise statement, written in a machine processable language, about the purpose and behavior of a program. Specifications are written in languages that are just as precise as programming languages, but have additional capabilities that increase their power of expression. The termi nology formal specification is sometimes used to emphasize the modern meaning. For us, all specifications are formal. The use of specifications as an integral part of a program opens up a whole new area of programming - progmmming with specifications. This book describes how to use specifications in the process of building programs, debugging them, and interfacing them with other programs. It deals with a new trend in programming - the evolution of specification languages from the current generation of programming languages. And it describes new strategies and styles of programming that utilize specifications. The trend is just beginning, and the reader, having finished this book, will viii Preface certainly see that there is much yet to be done and to be discovered about programming with specifications.

This book gives an introduction to the specification of programs, and some techniques that may be used to prove correctness of programs. Before mentioning any programming language an abstract execution model with an operational semantics is introduced, which is used for proving correctness. This execution model starts with recursive functions on which several features are added. When the execution model is introduced the transformation of recursive functions to tail recursive functions is treated, whenever such is possible. Iterative algorithms and the transformation between iterative algorithms and tail recursive functions is the next topic of the book. At that moment enough ingredients are there to introduce partial and total correctness of algorithms. Finally the implementation of algorithms in the programming languages ML and Pascal is treated.

Providing a thorough treatment of most elementary program development techniques, this revised edition covers topics such as procedures, parameters, recursion and data refinement, with the integration of specification, development and coding, based on ordinary (classical) logic.

Following the sucess of the first edition, the authors have updated and revised this bestselling textbook to take into account the changes in the subject over the past 5 years.

This book is suitable for use in a university-level first course in computing (CS1), as well as the increasingly popular course known as CS0. It is difficult for many students to master basic concepts in computer science and programming. A large portion of the confusion can be blamed on the complexity of the tools and materials that are traditionally used to teach CS1 and CS2. This textbook was written with a single overarching goal: to present the core concepts of computer science as simply as possible without being simplistic.

Building software often seems harder than it ought to be. It takes longer than expected, the software's functionality and performance are not as wonderful as hoped, and the software is not particularly malleable or easy to maintain. It does not have to be that way. This book is about programming, and the role that formal specifications can play in making programming easier and programs better. The intended audience is practicing programmers and students in undergraduate or basic graduate courses in software engineering or formal methods. To make the book accessible to such an audience, we have not presumed that the reader has formal training in mathematics or computer science. We have, however, presumed some programming experience. The roles of fonnal specifications Designing software is largely a matter of combining, inventing, and planning the implementation of abstractions. The goal of design is to describe a set of modules that interact with one another in simple, well defined ways. If this is achieved, people will be able to work independently on different modules, and yet the modules will fit together to accomplish the larger purpose. In addition, during program maintenance it will be possible to modify a module without affecting many others. Abstractions are intangible. But they must somehow be captured and communicated. That is what specifications are for. Specification gives us a way to say what an abstraction is, independent of any of its implementations.