Ability to configure function for formatting code

[kommen]

It would be nice to have the ability to configure the function used for formatting code (i.e cider-format-buffer).

The relevant repl middleware function:

cider-nrepl/src/cider/nrepl/middleware/format.clj

Lines 12 to 16 in ce42411

	(def ^:private reformat-string
	(delay
	(do
	(require 'cljfmt.core)
	(resolve 'cljfmt.core/reformat-string))))

We'd like to use https://github.com/kkinnear/zprint instead cljfmt.

For pretty printing, configuring the desired library is already supported:

cider-nrepl/src/cider/nrepl/middleware/pprint.clj

Lines 39 to 43 in f406dff

	(defn- resolve-pprint-fn
	[sym]
	(if-let [pp-fn (-> sym u/as-sym find-var)]
	pp-fn
	(throw (IllegalArgumentException. (format "%s is not resolvable to a var" sym)))))

For now, and in case somebody else wants to use zprint with cider, we use the following approach to change reformat-string:

(alter-var-root
  #'cider.nrepl.middleware.format/reformat-string
  (constantly (delay #(zprint/zprint-file-str % "<stdin>")))

Is the ability to configure this properly and out of the box, like for pretty printing, something the project would be interested in?

[bbatsov]

Yeah, certainly.

Ideally this should be done in a way that that doesn't make cider-nrepl depend directly on several libraries, though.