Elisp related to 2021 March 5 Emacs-SF Demo of Nested Hydra Menus by Mike Wright

demo-nested-hydra-menus.el

;;; demo-nested-hydra-menus.el --- Emacs SF hydra gist -*- lexical-binding: t; -*-
;; Elisp related to 2021 March 5 Emacs-SF Demo of Nested Hydra Menus by Mike Wright
;;
;; (use-package hydra :ensure t)
;; 
(progn
  (require 'hydra)
  (defvar hydra-stack nil)

  (defun hydra-push (expr)
    (push `(lambda () ,expr) hydra-stack))

  (defun hydra-pop ()
    (interactive)    
    (let ((x (pop hydra-stack)))
      (when x
        (funcall x))))
  (defun hydra-reset ()
    "Reset the stack to empty."
    (interactive)
    (setq hydra-stack '()))
  (defhydra hydra-low (:color amaranth)
    "low"
    ("e" (message "do something else") "demo something else")
    ("i" (message "do it") "demo it")
    ("p" show-paren-mode "toggle paren matching")
    ("s" (message "do something") "demo something")
    ("w" whitespace-mode "toggle whitespace")
    ("+" text-scale-increase "bigger text")
    ("-" text-scale-decrease "smaller text")
    ("b" hydra-pop "back" :color blue )
    ("q" hydra-reset "quit" :exit t))
  (defhydra hydra-mid (:color teal)
    "mid"
    ("l" (progn
           (hydra-low/body)
           (hydra-push '(hydra-mid/body))) "low")
    ("b" hydra-pop "back" :color blue)
    ("q" hydra-reset "quit" :exit t))
  (defhydra hydra-high (:color teal)
    "high"
    ("m" (progn
           (hydra-mid/body)
           (hydra-push '(hydra-high/body)))
     "middle")   
    ("q" hydra-reset "quit" :exit t))
  (global-set-key (kbd "s-1") 'hydra-high/body))

The actual elisp code I demoed was much larger (multiple files) and coupled to a lot of non-hydra code. To simplify things, I created this self-contained demo file.

Also, the code I demoed on March 5th had a bug that prevented returning from nested menus, so this code has a fix for that.

I also demoed something very similar to this on 3/19 using yasnippets.