Revised5.91 Report on the Algorithmic Language Scheme

The report gives a defining description of the programming language Scheme. Scheme is a statically scoped and properly tail-recursive dialect of the Lisp programming language invented by Guy Lewis Steele Jr. and Gerald Jay Sussman. It was designed to have an exceptionally clear and simple semantics and few different ways to form expressions. A wide variety of programming paradigms, including imperative, functional, and message passing styles, find convenient expression in Scheme. The introduction offers a brief history of the language and of the report. It also gives a short introduction to the basic concepts of the language. Chapter 2 explains Scheme’s number types. Chapter 3 defines the read syntax of Scheme programs. Chapter 4 presents the fundamental semantic ideas of the language. Chapter 5 defines notational conventions used in the rest of the report. Chapters 6 and 7 describe libraries and scripts, the basic organizational units of Scheme programs. Chapter 8 explains the expansion process for Scheme code. Chapter 9 explains the Scheme base library which contains the fundamental forms useful to programmers. The next set of chapters describe libraries that provide specific functionality: Unicode semantics for characters and strings, binary data, list utility procedures, a record system, exceptions and conditions, I/O, specialized libraries for dealing with numbers and arithmetic, the syntax-case facility for writing arbitrary macros, hash tables, enumerations, and various miscellaneous libraries. Chapter 21 describes the composite library containing most of the forms described in this report. Chapter 22 describes the eval facility for evaluating Scheme expressions represented as data. Chapter 23 describes the operations for mutating pairs. Chapter 24 describes a library with some procedures from the previous version of this report for backwards compatibility. Appendix A provides a formal semantics for a core of Scheme. Appendix B contains definitions for some of the derived forms described in the report. The report concludes with a list of references and an alphabetic index.