How do I add custom hierarchical keybindings?

Question

I am looking for a compact way to store a lot of shortcut key bindings. This is my current idea, for which I'm looking for help how to add this into my Emacs config:

I would like to make F9 "my" key, that opens up a hierarchical menu of (global) key bindings.

When pressing F9, I'd like a submenu to open that shows e.g.:

o - org-mode submenu
a - show org-mode agenda
w - org-wiki submenu
b - org-brain submenu

If I press F9-a, I'd like to directly execute the M-x org-agenda command.

But by pressing F9-w, I get a new submenu opened that e.g. shows this:

# Org-wiki submenu
i - Show Wiki index
n - Add new Wiki page

If my final keystroke sequence is F9-w-i, I want the command M-x org-wiki-index executed.

• Does something like this exist already?
• Is there a better solution?
• If no, how would I add something like this in my emacs config?

/Edit: I think what I want is to write my custom version of the M-x org-agenda command.

Answer 1

As @icarus suggested, hydra is the way to go here. Check out my solution that is similar to what you want here: https://github.com/jkitchin/scimax/blob/master/scimax-hydra.el

there are submenus of keys that open new hydras. I have mine bound to f12, and then remapped caps lock to be f12. It is convenient for me.

Answer 2

If you install and enable which-key then Emacs will do that (albeit with more compact formatting) for every prefix binding, including your custom ones.