Everything is a function ? even structs and types ?

functor.el

(setq lexical-binding t)

(defun make-struct (fields)
  (lambda (values)
    (let ((map (-zip fields values)))
     (lambda (field)
       (assoc field map)))))

;;; generic
(setq s (make-struct '(:a :b :c)))
(setq u (funcall s '(1 2 3)))
(funcall u :a)
(funcall u :b)
(funcall u :c)
(-map (lambda (f) (funcall u f)) '(:a :b :c)) ; u -> u

;;; specific
(setq Person (make-struct '(:name :age :city)))
(setq john (funcall Person '(John 23 London)))
(funcall john :age)