Emacs: setting up Apheleia to use Prettier and Zprint

Apheleia is an awesome Emacs package for formatting code quickly using external command line tools like prettier. Not only is it fast but it also does a great job at maintaining point position relative to its surroundings (which has been one of my minor frustrations with other Emacs formatters). It's also language agnostic so you can use it with any language that has a command line formatting tool. This post will cover setting up apheleia with prettier (for JavaScript) and zprint (for Clojure).

Though outside the scope of this post, for those that are interested, apheleia does some really impressive stuff under the hood with RCS patches and dynamic programming algorithm for string alignment.

Apheleia

Set up aphelia using use-package:

(use-package apheleia
  :straight (apheleia :host github :repo "raxod502/apheleia")
  :config
  (apheleia-global-mode t))

Prettier

If you use JavaScript you can set up prettier:

(use-package apheleia
  :straight (apheleia :host github :repo "raxod502/apheleia")
  :config
  (setf (alist-get 'prettier apheleia-formatters)
        '(npx "prettier"
              "--trailing-comma"  "es5"
              "--bracket-spacing" "true"
              "--single-quote"    "true"
              "--semi"            "false"
              "--print-width"     "100"
              file))
  (add-to-list 'apheleia-mode-alist '(rjsx-mode . prettier))
  (apheleia-global-mode t))

Notice we can pass in formatting defaults.

Zprint

If use Clojure you can set up zprint:

(use-package apheleia
  :straight (apheleia :host github :repo "raxod502/apheleia")
  :config
  (setf (alist-get 'clj-zprint apheleia-formatters)
        '("clj-zprint"
          "{:style [:community :justified] :map {:comma? false}} <"
          file))
  (add-to-list 'apheleia-mode-alist '(clojure-mode . clj-zprint))
  (apheleia-global-mode t))

Again we can pass in formatting defaults.

Both

If you are fortunate enough to use both Javascript and Clojure you can set them up together:

(use-package apheleia
  :straight (apheleia :host github :repo "raxod502/apheleia")
  :config
  (setf (alist-get 'prettier apheleia-formatters)
        '(npx "prettier"
              "--trailing-comma"  "es5"
              "--bracket-spacing" "true"
              "--single-quote"    "true"
              "--semi"            "false"
              "--print-width"     "100"
              file))
  (setf (alist-get 'clj-zprint apheleia-formatters)
        '("clj-zprint"
          "{:style [:community :justified] :map {:comma? false}} <"
          file))
  (add-to-list 'apheleia-mode-alist '(rjsx-mode . prettier))
  (add-to-list 'apheleia-mode-alist '(clojure-mode . clj-zprint))
  (apheleia-global-mode t))

The full example can be found in my Emacs config here.

Checkout this post for installing zprint with homebrew.