Introduction to the AutoLISP Programming Language

Abstract

In this inaugural issue of the Graphic Codes column, dedicated to programming languages for graphic software, we begin with an introduction to the AutoLISP language associated with AutoCAD. This first instalment also presents a simple routine developed from the sample code introduced here; it will be followed by a second and third instalment, offering more in-depth insights and more complex AutoLISP routines. Later on, the Graphic Codes column will also cover other programming languages, starting with introductory basics.
Creating custom AutoLISP routines allows users to automate and extend AutoCAD’s capabilities according to their needs. AutoLISP is a simplified dialect of the LISP language, adapted for AutoCAD. LISP was created in 1958 by John McCarthy as a formal language to study the computability of recursive functions on symbolic expressions, and it supports a functional programming style. Its name derives from its structure, based on expressions consisting of dynamic lists of elements enclosed in parentheses, which are processed at runtime (LISt Processing). The broader diffusion of LISP occurred through dialects integrated into commonly used software applications.
In AutoCAD, LISP was introduced in 1986 under the name AutoLISP, becoming a versatile programming language highly interoperable with the software. It retains the core features of the original LISP while adding a wide range of specific functions for handling AutoCAD’s geometric data and graphic entities. In 1997, Autodesk incorporated additional functionality and renamed it Visual LISP.