Common Lisp literal symbols: Which form correctly assigns the <em>symbol</em> x (not the value of x) to the variable y?

Introduction / Context:
In Lisp, symbols can be manipulated as data. To store the literal symbol x in a variable y, you must prevent evaluation of x. The quote operator (' or (quote …)) serves this purpose by yielding the symbol itself instead of its bound value.

Given Data / Assumptions:

• We want y to hold the symbol x, not x's current value.
• setq assigns to a variable without evaluating the variable name.
• We must ensure the right-hand side is the symbol object.

Concept / Approach:
Use (setq y 'x'). Here, 'x evaluates to the symbol X. setq stores that symbol in y. Any forms that use ‘‘=’’ syntax are not Lisp and are therefore incorrect.

Step-by-Step Solution:

Verification / Alternative check:
In a REPL, after (setq y 'x'), (symbolp y) returns T and (eq y 'x') returns T.

Why Other Options Are Wrong:

• (setq y x) assigns the value of x, not the symbol.
• Forms using ‘‘=’’ are not valid Lisp syntax.

Common Pitfalls:
Forgetting to quote the symbol or confusing set and setq semantics can result in unintended variable dereferencing.

Final Answer:
(setq y 'x')