Special Form Entry: PROGN
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Special Form Entry: PROGN
Name
progn
Class
Special Form
Syntax
(progn [expr ...])
Arguments and Values
- zero or more expressions
Description
Evaluates expressions sequentially.
Evaluation Rules
- evaluate each expression left to right
Return Values
- returns the value of the last expression
- returns nil if no expressions are supplied
Side Effects
Side effects are those of the evaluated expressions.
Exceptional Situations
Malformed syntax is erroneous.
Examples
(progn (setq a 1) (setq b 2) b) => 2
Compatibility
Autodesk classifies progn as a special form.
Availability
- AutoCAD 2026: documented (per Autodesk reference page).
- BricsCAD V26: presumed compatible (no contradicting page found).
- Status: AutoCAD documented; BricsCAD presumed-both pending Phase 4 verification.
Source Notes
- [About Special Forms (AutoLISP)](https://help.autodesk.com/cloudhelp/2017/ENU/AutoCAD-AutoLISP/files/GUID-F992EAA3-AFFC-425D-B7C9-6A9CB0EA2768.htm)
- Status: documented as a special form; detailed entry still partly inferred from stable Lisp usage.