Unicode input - abo-abo/hydra GitHub Wiki
Hydras are great for documenting key bindings that are seldom used. Unicode characters are a prime example: they are available in all modern emacsen as long as you have the right font to display them. The document string takes all guesswork out from selecting the right one by showing you the Unicode characters.
See the story behind this hydra.
(defun my/insert-unicode (unicode-name)
"Same as C-x 8 enter UNICODE-NAME."
(insert-char (gethash unicode-name (ucs-names))))
(global-set-key
(kbd "C-x 9")
(defhydra hydra-unicode (:hint nil)
"
Unicode _e_ โฌ _s_ ZERO WIDTH SPACE
_f_ โ _o_ ยฐ _m_ ยต
_r_ โ _a_ โ
"
("e" (my/insert-unicode "EURO SIGN"))
("r" (my/insert-unicode "MALE SIGN"))
("f" (my/insert-unicode "FEMALE SIGN"))
("s" (my/insert-unicode "ZERO WIDTH SPACE"))
("o" (my/insert-unicode "DEGREE SIGN"))
("a" (my/insert-unicode "RIGHTWARDS ARROW"))
("m" (my/insert-unicode "MICRO SIGN"))))