LISP 1.5 Programmer's Manual

Written as a reference for programmers, this manual introduces LISP, a formal mathematical language built for manipulating symbols rather than numbers alone. Its applications include symbolic calculus, circuit analysis, mathematical logic, game-playing programs, and other areas of artificial intelligence. The author, John McCarthy, worked with several collaborators on the text.

LISP stands apart from most programming languages in three ways. Its data take the form of S-expressions, which can be any length and form branching, tree-like structures from which meaningful parts are easy to extract. Memory is mostly devoted to storing these expressions as list structures. The language itself serves as the notation for describing how those expressions get processed. Finally, LISP can read and run programs that are themselves written as S-expressions, so, much like machine code, it can produce new programs as it runs.