I've been playing around with keymaps. Apparently they can be used to create menus that give the user a visual list of options. The canonical way to make them is aparently with make-sparse-keymap to create the menu and define-key to add options to it, but this causes some confusing behaviour.

Take the following example:

(let ((menu (make-sparse-keymap "My menu")))
  (define-key menu "a"
    '(menu-item "Foo" foo))
  (define-key menu "b"
    '(menu-item "Bar" bar))
  menu)

Yields the following:

(keymap (98 menu-item "Bar" bar) (97 menu-item "Foo" foo) "My menu")

Each new entry is added to the top of the list, so when the menu is displayed, they're listed in reverse order. This is very counter intuitive.

Now, I understand that the nature of lists in lisp make inserting an element at the top of the list less computationally expensive, but when you've already got to walk the whole list anyway to ensure the key binding isn't already present, this no longer feels like an adequate excuse.

Am I missing something?

#emacs #elisp