LISP I Programmer's Manual - Software Preservation Group

The symbol - a in label(a,e) is also bound, that is, it maybe altered systematically without changing the meaning of theexpression. It behaves differently from a variable bound by aA, however.2.2 Symbolic ExpresSionsWe shall first define a class of symbolic expressions interms of ordered pairs and lists. Then we shall define fiveelementary functions and predicates, and build from them bycomposition, conditional expressions, and recursive definitionsan extensive class of functions of which we shall give a numberof examples. We shall then show how these functions can beexpressed as symbolic expressions, and we shall define a universalfunction apply that allows us to compute from the expressionfor a given function its value for given arguments.Finally, we shall define some functions with functions as argumentsand give some useful examples.a. A Class of Symbolic ExpressionsWe shall now define the S-expressions (S stands for symbolic).They are formed by. using the special characters.)(and an infinite set of distinguishable atomic symbols. Foratomic symbols, we shall use strings of capital Latin lettersand digits. Examples of atomic symbols areAAB AAPPLEPIENUMBER3