Higher-order functions in Elisp

Question

I created a function that returns a function in Elisp:

(defun singleton-set (elem)
  (defun f (n) (= n elem))
  f)

I try to run this in IELM, a

Answer 1

(defun singleton-set (elem)
  `(lambda (n) (= n ,elem))

See: elisp functions as parameters and as return value