This hydra maps h and k for cycling through Mono fonts installed on
your system:
(require 's)
(require 'dash)
(defun leoc/s-contains-mono (name)
(and (s-contains-p "mono" name t)
(not (s-contains-p "italic" name t))
(not (s-contains-p "bold" name t))))
(setq leoc/frame-font-loop
(-filter
'leoc/s-contains-mono
(x-list-fonts "*" nil (selected-frame))))
(setq leoc/current-frame-font-index 0)
(defun leoc/cycle-frame-font (direction)
(let* ((current-font-index leoc/current-frame-font-index)
(next-font-index (mod (+ current-font-index direction) (length leoc/frame-font-loop)))
(next-font (nth next-font-index leoc/frame-font-loop)))
(message "Setting new frame font (index %S): %S" leoc/current-frame-font-index next-font)
(set-frame-font next-font)
(if (null (assq 'font default-frame-alist))
(add-to-list 'default-frame-alist
`(font . ,next-font))
(setcdr (assq 'font default-frame-alist) next-font))
(setq leoc/current-frame-font-index next-font-index)))
(defun leoc/cycle-next-frame-font ()
"Cycle to next font in list."
(interactive)
(leoc/cycle-frame-font +1))
(defun leoc/cycle-prev-frame-font ()
"Cycle to previous font in list."
(interactive)
(leoc/cycle-frame-font -1))
(defhydra hydra-frame-font nil
"Cycle through mono fonts"
("k" leoc/cycle-next-frame-font "Next font")
("j" leoc/cycle-prev-frame-font "Previous font"))