GNU Emacs Lisp Reference Manual

8.3: Kinds of Forms

A Lisp object that is intended to be evaluated is called a form. How Emacs evaluates a form depends on its data type. Emacs has three different kinds of form that are evaluated differently: symbols, lists, and ``all other types''. This section describes all three kinds, starting with ``all other types'' which are self-evaluating forms.

• Self-Evaluating Forms Forms that evaluate to themselves.
• Symbol Forms Symbols evaluate as variables.
• Classifying Lists How to distinguish various sorts of list forms.
• Function Indirection When a symbol appears as the car of a list, we find the real function via the symbol.
• Function Forms Forms that call functions.
• Macro Forms Forms that call macros.
• Special Forms ``Special forms'' are idiosyncratic primitives, most of them extremely important.
• Autoloading Functions set up to load files containing their real definitions.