Attempt to write the derivative as a first class operator

derivator-first-class.lisp

(defparameter *maths-functions* (list))

(defmacro defun-maths (func-name args core)
  "appends the code of func-name into maths-functions."
  `(progn
     (push (list (quote ,func-name) (quote ,@args) (quote ,core)) *maths-functions*)
     (defun ,func-name ,args ,core)))



(defparameter *derivatives*
  (list 'cos '(* -1 sin)
        'sin 'cos
        '+ '+))

(defun get-derivative (func)
  (getf *derivatives* func))

(defun derivative (expr variable)
  (let* ((func (car expr))
         (args (cdr expr))
         (der (get-derivative func)))
    ()))