(format t "Hello, world!~%")

Run with a Common Lisp implementation such as SBCL:

sbcl --script main.lisp

This prints a line in Common Lisp using format, which is a flexible function for building and writing text.

(defparameter *name* "Dan")
(defparameter *count* 1)
(defparameter *active* t)

These global parameters hold simple values you can reuse across expressions.

(defun greet (name)
  (format nil "Hello, ~A!" name))

(greet "world")

This defines a function and then calls it. Lisp keeps the function shape compact, even for small reusable helpers.