Hello world!

— Why don't you write a function to greet the world?
— Great idea. I'll do it in Emacs Lisp.
— Good grief, in what? Did I hear "Emacs"? Does Lisp still exist?
— (...)
— Fine, fine. But seriously, Lisp?
— Ok, ok, nevermind. I'll pick another one...

(function hello-world ()             ## <--- Bash, actually
  (interactive |&:)
  (clear)
  (echo "Hello world!"
      (let var
          (if true; then
               (echo
                 ((+ 42))
                 (echo "How are you?"))
             fi)
          (cat < <(printf "%s, " "Hello there"
                    (printf "%s "    "my dear")
                      (printf "%s."    "world"))
             (echo
               (echo
                 (printf "%s — %s.\n" \
                         "Hello world"\
                         "and have a great day"))))))
  (hello-world))

And with this, we get started.