Common Lisp assignment semantics: Which function evaluates both the variable argument and the value expression when assigning, thereby allowing indirect (symbol-valued) assignment?

Introduction / Context:
In Common Lisp, variable assignment can be done with multiple forms. Understanding when the variable name is evaluated versus treated as a literal symbol is crucial, especially for indirect assignments and metaprogramming tasks.

Given Data / Assumptions:

• We compare set and setq semantics.
• We care about whether the first argument (the variable) is evaluated.
• Goal: identify the form that evaluates both its arguments.

Concept / Approach:
setq assigns to a named variable without evaluating the variable name; only the value expression is evaluated. By contrast, set evaluates its first argument to obtain a symbol and evaluates its second argument for the new value. Thus, set supports indirect assignment when the symbol to assign is itself computed.

Step-by-Step Solution:

Verification / Alternative check:
Test in a REPL: (let ((s 'x')) (set (symbol-value 's') 5)) demonstrates evaluated first arg; (setq s 5) would instead set variable s, not X.

Why Other Options Are Wrong:

• setq does not evaluate the variable name.
• add and ‘‘eva’’ are not standard Common Lisp assignment primitives.

Common Pitfalls:
Passing a raw symbol to set without quoting or ensuring evaluation yields a symbol leads to errors; ensure the first argument evaluates to a symbol object.

Final Answer:
set