Elisp: Special Form

Standard Evaluation Strategy

Normally, arguments passed to a function are evaluated, in order. In elisp, this is called standard evaluation strategy.

Non-Standard Evaluation Strategy

However, for some function, evaluating arguments in order does not make sense. For example, conditional construct if, or local variable construct let. These functions, are said to have non-standard evaluation strategy.

Macro and Special Form

Of functions that are non-standard evaluation, they are either macro or special form.

• Macros are defined by lisp expressions with defmacro. User can define them.
• Special Forms are written in C.

Example of Special Forms

1. and
2. or
3. catch
4. if
5. while
6. cond
7. condition-case
8. defconst
9. defvar
10. let
11. let*
12. prog1
13. prog2
14. progn
15. setq
16. setq-default
17. interactive
18. lambda
19. quote
20. function
21. save-current-buffer
22. save-excursion
23. save-restriction
24. track-mouse
25. unwind-protect

• Macros (ELISP Manual)
• Special Forms (ELISP Manual)