A function to add pretty comments in Emacs

pretty-comments.el

(defun insert-comment-with-description (comment-syntax comment)
  "Inserts a comment with '―' (Unicode character: U+2015) on each side."
  (let* ((comment-length (length comment))
         (current-column-pos (current-column))
         (space-on-each-side (/ (- fill-column
                                   current-column-pos
                                   comment-length
                                   (length comment-syntax)
                                    ;; Single space on each side of comment
                                   (if (> comment-length 0) 2 0)
                                   ;; Single space after comment syntax sting
                                   1)
                                2)))
    (if (< space-on-each-side 2)
        (message "Comment string is too big to fit in one line")
      (progn
        (insert comment-syntax)
        (insert " ")
        (dotimes (_ space-on-each-side) (insert "―"))
        (when (> comment-length 0) (insert " "))
        (insert comment)
        (when (> comment-length 0) (insert " "))
        (dotimes (_ (if (= (% comment-length 2) 0)
                      space-on-each-side
                      (- space-on-each-side 1)))
          (insert "―"))))))

;; For Clojure
(defun clj-insert-comment-with-description ()
  "Inserts a pretty Clojure comment."
  (interactive)
  (insert-comment-with-description ";;" (read-from-minibuffer "Comment: ")))

;; For C
(defun c-insert-comment-with-description ()
  "Inserts a pretty C comment."
  (interactive)
  (insert-comment-with-description "//" (read-from-minibuffer "Comment: ")))