AutoLISP assumes that a list is an expression that needs to be evaluated. The function must be the first element in a list and its arguments must immediately follow it. A generalized AutoLISP function would look this way:

  • AutoLISP evaluates the expression depending on the function definition and the explicit arguments that are designated.
  • Some functions have required arguments and some have both required and optional arguments. In this book we will designate optional arguments in brackets, [optional argument]. The brackets are not used in the actual routine.

Examples
We’ve already seen several examples of AutoLISP functions: the basic math functions. In generalized form, they would look like this: