Convert the current region in emacs from JSON to EDN using Bork's Jet.

json->edn.el

;; Uses https://github.com/borkdude/jet

;; On OSX, install jet with:

;; brew install borkdude/brew/jet

;; I invoke this with M-x, you might want to bind it to a key
(defun json->edn ()
  (interactive)
  (shell-command-on-region (region-beginning)
                           (region-end)
                           "jet --pretty --keywordize keyword --from json --to edn"
                           (current-buffer)
                           t))

Tweaked it a bit into the following:

(defun json->edn ()
  "Convert the selected region, or entire file, from JSON to EDN."
  (interactive)
  (let ((b (if mark-active (region-beginning) (point-min)))
        (e (if mark-active (region-end) (point-max)))
        (jet (when (executable-find "jet")
               "jet --pretty --keywordize keyword --from json --to edn")))
    (if jet
      (let ((p (point)))
        (shell-command-on-region b e jet (current-buffer) t)
        (goto-char p))
      (user-error "Could not find jet installed"))))

How can I install this function in my emacs?