Lisp REPL behavior: When a top-level function call is entered, what sequence of actions does the Lisp system perform in the classic Read–Eval–Print loop?

Introduction / Context:
A hallmark of Lisp environments is the interactive Read–Eval–Print Loop (REPL). Understanding how the REPL processes expressions is key to debugging AI programs, experimenting with data structures, and building incremental prototypes.

Given Data / Assumptions:

• The prompt accepts a function call form (operator followed by operands).
• The system follows the canonical REPL cycle.
• We consider a normal, successful evaluation without reader or runtime errors.

Concept / Approach:
The REPL cycles through three main steps: read (parse the textual input into Lisp objects), eval (evaluate the expression—i.e., call the function on evaluated arguments under Lisp's applicative order), and print (render the returned value to the console using the printer). Many Lisp implementations add a fourth “loop” step to continue interaction.

Step-by-Step Solution:
Read: the reader converts characters into a symbolic expression.Eval: the evaluator resolves symbols, applies functions, and computes results.Print: the printer outputs the returned value in a readable form.Combine: all three are performed in sequence on each top-level input.

Verification / Alternative check:
Try a simple call, e.g., (+ 1 2). The system reads the list, evaluates it to 3, then prints 3. Errors during reading (e.g., mismatched parentheses) or evaluation (e.g., undefined function) confirm the distinct phases.

Why Other Options Are Wrong:
Single-phase options omit essential steps; REPL does all three.

None of the above: incorrect because “All of the above” maps to the REPL exactly.

Common Pitfalls:
Confusing macro expansion with reading or printing; macros expand during evaluation but are separate from the reader and printer.

Final Answer:
All of the above