Lisp 1.5 Programmer's Manual

The LISP language is designed primarily for symbolic data processing used forsymbolic calculations in differential and integral calculus, electrical circuit theory, mathematicallogic, game playing, and other fields of artificial intelligence.The manual describes LISP, a formalmathematical language. LISP differs from most programming languages in three important ways. Thefirst way is in the nature of the data. In the LISP language, all data are in the form of symbolicexpressions usually referred to as S-expressions, of indefinite length, and which have a branchingtree-type of structure, so that significant subexpressions can be readily isolated. In the LISPsystem, the bulk of the available memory is used for storing S-expressions in the form of liststructures. The second distinction is that the LISP language is the source language itself whichspecifies in what way the S-expressions are to be processed. Third, LISP can interpret and executeprograms written in the form of S-expressions. Thus, like machine language, and unlike most otherhigh level languages, it can be used to generate programs for further executions.

John McCarthy is Professor Emeritus in the Department of Computer Science, Stanford University.