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Chapter 9: Extended Examples
Overview
Two warped, two-armed spirals and one polyhedron.
Chapters 2 and 3, and a few are major projects.Section 9.1 presents a simple matrix multiplication package. It demonstrates a set of procedures that could be written in almost any language. Its most interesting features are that all multiplication operations are performed by calling a single generic procedure, mul, which calls the appropriate help procedure depending upon the dimensions of its arguments, and that it dynamically allocates results of the proper size. Section 9.2 presents a useful merge sorting algorithm for ordering lists according to arbitrary predicates. Section 9.3 describes a syntactic form that is used to construct sets. It demonstrates a simple but efficient syntactic transformation from set notation to Scheme code. Section 9.4 presents a word counting program borrowed from The C Programming Language [15], translated from C into Scheme. It shows character and string manipulation, data structure creation and manipulation, and basic file input and output. Section 9.5 presents a basic Scheme printer that supports both write and display for all standard object types. Section 9.6 presents a simple formatted output facility similar to those found in many Scheme systems and in other languages. Section 9.7 presents a simple interpreter for Scheme that illustrates Scheme as a language implementation vehicle while giving an informal operational semantics for Scheme as well as a useful basis for investigating extensions to Scheme. Section 9.8 presents a small, extensible abstract object facility that could serve as the basis for an entire object-oriented subsystem. Section 9.9 presents a recursive algorithm for computing the Fourier transform of a sequence of input values. It highlights the use of Scheme's complex arithmetic. Section 9.10 presents a concise unification algorithm that shows how procedures can be used as continuations and as substitutions (unifiers) in Scheme. Section 9.11 describes a multitasking facility and its implementation in terms of continuations.
