Strategies for building large systems that can be easily adapted for new situations with only minor programming modifications. Time pressures encourage programmers to write code that works well for a narrow purpose, with no room to grow. But the best systems are evolvable; they can be adapted for new situations by adding code, rather than changing the existing code. The authors describe techniques they have found effective--over their combined 100-plus years of programming experience--that will help programmers avoid programming themselves into corners. The authors explore ways to enhance flexibility by: - Organizing systems using combinators to compose mix-and-match parts, ranging from small functions to whole arithmetics, with standardized interfaces - Augmenting data with independent annotation layers, such as units of measurement or provenance - Combining independent pieces of partial information using unification or propagation - Separating control structure from problem domain with domain models, rule systems and pattern matching, propagation, and dependency-directed backtracking - Extending the programming language, using dynamically extensible evaluators

Die UEbersetzung der bewahrten Einfuhrung in die Informatik, entstanden am Massachusetts Institute of Technology (MIT), wird seit Jahren erfolgreich in der Lehre eingesetzt. Schritt fur Schritt werden Konstruktion und Abstraktion von Daten und Prozeduren dargestellt. Von der Modularisierung bis zum Problemloesen mit Registermaschinen werden verschiedene Programmierparadigmen entwikckelt und die effektive Handhabung von Komplexitat gezeigt. Als Programmiersprache wird SCHEME verwendet, ein Dialekt von LISP. Alle Programme laufen in jeder dem IEEE-Standard entsprechenden SCHEME-Implementierung.

A new edition of a book, written in a humorous question-and-answer style, that shows how to implement and use an elegant little programming language for logic programming. The goal of this book is to show the beauty and elegance of relational programming, which captures the essence of logic programming. The book shows how to implement a relational programming language in Scheme, or in any other functional language, and demonstrates the remarkable flexibility of the resulting relational programs. As in the first edition, the pedagogical method is a series of questions and answers, which proceed with the characteristic humor that marked The Little Schemer and The Seasoned Schemer. Familiarity with a functional language or with the first five chapters of The Little Schemer is assumed. For this second edition, the authors have greatly simplified the programming language used in the book, as well as the implementation of the language. In addition to revising the text extensively, and simplifying and revising the "Laws" and "Commandments," they have added explicit "Translation" rules to ease translation of Scheme functions into relations.