:faster-than-light /memes


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A cider jack in command for nbb.


Nbb is a beatiful parasite. A node script that is an interpreter for Clojurescript. You get the upsides of Node.js + it is Clojure.

Want to try out some npm packages? Sure, just make a package.json, works instant, is part of the design principles of nbb.

You get Clojures immutable data structures, polymorphism constructs, a repl, etc.

On the tooling side, you might be surprised how far nbb gets with very little.

Scratching (in space) is very usefull and nbb is a natural fit for a quick cljs repl.

Update 2:

You can jack in Nbb nowadays with cider-jack-in-cljs then select nbb.

Alternatively, if you have cider d292d8d7eea5d3a12c138687133761a7256b1705

We can define jack in commands like so:

(defun cider-jack-in-nbb-2 ()
  "Start a Cider nREPL server with the `nbb nrepl-server` command."
  (cider-jack-in '(:jack-in-cmd "nbb nrepl-server")))

You can also set a project jack-in-cmd in .dir-locals by setting cider-jack-in-cmd locally.

  (cider-jack-in-cmd . "nbb nrepl-server")))

This is especially useful, if you have an nbb project. You can now call cider-jack-in-clj without the need to select anything further anymore.

Note: Commands and elisp below are workarounds we do not need anymore because Cider supports Nbb much better since recently!


This is no longer needed with cider 1.6. There is a dedicated nbb cider build tool now. I still also think my proposal here would be useful.

;; the equivalent of the proposed change
 (defun cider-dont-update-jack-in-cmd-when-given (params)
   (when (plist-get params :jack-in-cmd) params)))

;; now a nbb jack in command becomes:
(cider-jack-in '(:jack-in-cmd "nbb nrepl-server"))

Jack-in command

cider repl workaround

We currently need this workaround for sci-based cljs repls for cider:

(cider-register-cljs-repl-type 'nbb-or-scittle-or-joyride "(+ 1 2 3)")

(defun mm/cider-connected-hook ()
  (when (eq 'nbb-or-scittle-or-joyride cider-cljs-repl-type)
    (setq-local cider-show-error-buffer nil)
    (cider-set-repl-type 'cljs)))

(add-hook 'cider-connected-hook #'mm/cider-connected-hook)

Note: You do not need this workaround in recent versions of cider anymore.

the command

Unfortunately, cider does not have the concept of a nbb repl currently. I think cider-jack-in-resolve-command and similar functions could be thrown out and replaced with data.

So I went 1 level deeper to bypass ciders auto-detection of project type (+ jack in cmd):

(defun mm/cider-jack-in-nbb ()
  "Start a nbb nrepl process and connect."
  (let* ((cider-allow-jack-in-without-project t)
         (orig-buffer (current-buffer))
         (params '(:jack-in-cmd "nbb nrepl-server :port 0"
                   :cljs-repl-type nbb-or-scittle-or-joyride))
         (params (cider--update-project-dir
     (plist-get params :project-dir)
     (plist-get params :jack-in-cmd)
     (lambda (server-buffer)

This is what I wanted to say:

(defun mm/cider-jack-in-nbb ()
  "Start an nbb nrepl process and connect."
   '(:jack-in-cmd "nbb nrepl-server :port 0"
     :cljs-repl-type nbb-or-scittle-or-joyride)))

hack for the remaining issue

With this, you should get an error "ClojureScript is not available…". Until there is a fix in cider, you can hack it by redefining cider-verify-clojurescript-is-present:

;;; FIXME: https://github.com/clojure-emacs/cider/issues/3255
(defun cider-verify-clojurescript-is-present ()
  "Check whether ClojureScript is present."
  (unless (nrepl-dict-get (cider-sync-tooling-eval "cljs.core/inc") "value")
    (user-error "ClojureScript is not available.  See https://docs.cider.mx/cider/basics/clojurescript for details")))


Hehe, insta nbb repl. Works good.

Date: 2022-10-14 Fri 10:22

Email: Benjamin.Schwerdtner@gmail.com