Normative Rules

• numbers and strings self-evaluate
• nil and T are predefined values
• symbols evaluate to their bound values
• ordinary calls evaluate arguments before invocation unless the operator is a special form
• nil is false and every non-nil value is true in conditional contexts

Evaluation order is historically version-sensitive in error-reporting contexts. Autodesk explicitly notes that modern AutoLISP evaluates all arguments before checking argument types in at least some cases, unlike older releases.