Error starting CLJS REPL with Boot project

[ieure]

Expected behavior

I should get a working CLJS REPL when I run cider-jack-in-clojurescript.

Actual behavior

I get this stack trace:

  Show: Clojure Java REPL Tooling Duplicates All  (13 frames hidden)

1. Unhandled java.lang.ClassNotFoundException
   cemerick.piggieback

       URLClassLoader.java:  381  java.net.URLClassLoader/findClass
   DynamicClassLoader.java:   69  clojure.lang.DynamicClassLoader/findClass
          ClassLoader.java:  424  java.lang.ClassLoader/loadClass
   DynamicClassLoader.java:   77  clojure.lang.DynamicClassLoader/loadClass
          ClassLoader.java:  357  java.lang.ClassLoader/loadClass
                Class.java:   -2  java.lang.Class/forName0
                Class.java:  348  java.lang.Class/forName
                   RT.java: 2154  clojure.lang.RT/classForName
                   RT.java: 2163  clojure.lang.RT/classForName
             Compiler.java: 1017  clojure.lang.Compiler$HostExpr/maybeClass
             Compiler.java:  795  clojure.lang.Compiler$HostExpr/access$600
             Compiler.java: 6662  clojure.lang.Compiler/macroexpand1
             Compiler.java: 6692  clojure.lang.Compiler/macroexpand
             Compiler.java: 6766  clojure.lang.Compiler/eval
             Compiler.java: 6745  clojure.lang.Compiler/eval
                  core.clj: 3081  clojure.core/eval
                  main.clj:  240  clojure.main/repl/read-eval-print/fn
                  main.clj:  240  clojure.main/repl/read-eval-print
                  main.clj:  258  clojure.main/repl/fn
                  main.clj:  258  clojure.main/repl
               RestFn.java: 1523  clojure.lang.RestFn/invoke
    interruptible_eval.clj:   87  clojure.tools.nrepl.middleware.interruptible-eval/evaluate/fn
                  AFn.java:  152  clojure.lang.AFn/applyToHelper
                  AFn.java:  144  clojure.lang.AFn/applyTo
                  core.clj:  630  clojure.core/apply
                  core.clj: 1868  clojure.core/with-bindings*
               RestFn.java:  425  clojure.lang.RestFn/invoke
    interruptible_eval.clj:   85  clojure.tools.nrepl.middleware.interruptible-eval/evaluate
    interruptible_eval.clj:  222  clojure.tools.nrepl.middleware.interruptible-eval/interruptible-eval/fn/fn
    interruptible_eval.clj:  190  clojure.tools.nrepl.middleware.interruptible-eval/run-next/fn
                  AFn.java:   22  clojure.lang.AFn/run
   ThreadPoolExecutor.java: 1142  java.util.concurrent.ThreadPoolExecutor/runWorker
   ThreadPoolExecutor.java:  617  java.util.concurrent.ThreadPoolExecutor$Worker/run
               Thread.java:  745  java.lang.Thread/run

The REPL itself seems to sort of work, but any CIDER commands fail with a fresh exception.

Steps to reproduce the problem

1. Run boot -d seancorfield/boot-new new -t hoplon -n address-book
2. Open the one CLJS file in the template project:C-x C-f address-book/cljs/index.cljs.hl
3. Run M-x clojurescript-mode (if it isn't set up to .cljs.hl files already).
4. Press C-c M-J

CIDER version information

;; CIDER 0.14.0 (Berlin), nREPL 0.2.12
;; Clojure 1.8.0, Java 1.8.0_51

Lein/Boot version

Boot 2.6.0

Emacs version

Emacs 25.5.1

Operating system

macOS 10.12.1 "Sierra"

[dpsutton]

Ok. So I'm looking into this.

(cider-nrepl-send-request
 (list "op" "eval"
       "ns" (cider-current-ns)
       "session" nrepl-session
       "code" cider-cljs-lein-repl)
 (cider-repl-handler (current-buffer)))

This is the code in the callback function that begins the clojurescript repl. It gets the var cider-cljs-lein-repl var from the assoc list, but already the variable name is telling us what's wrong: its tied to lein.

You set a default value for how to conjure up a clojurescript repl, and I've never really liked this style. And here, we aren't using lein and we must know how to crank up a repl. Apparently the thing we want is from a library called boot-cljs-repl. And since we don't have this, there doesn't seem to be an easy way to get a clojurescript repl from this project.

I'm new to boot and cljs, but apparently the standard way to interact with this is to jack-in and then run (dev), one of the defined tasks. This will crank up the watcher and compile files, etc.

[dpsutton]

If boot tasks can be counted on to always have a task called dev, we could determine that we are in a boot project and launch the dev task. Otherwise, if these tasks are arbitrarily named, I'm not sure how we could reliably launch anything with boot.

[dpsutton]

And there's this from a boot library

The cljs-repl-env task

There is a cljs-repl-env task that doesn't start a new nREPL server which you can use via cider-jack-in. An example is shown below.

(deftask dev []
  (comp (watch)
        (cljs-repl-env) ; order is important!!
        (cljs)))

M-x cider-jack-in
boot.user=> (def p (future (boot (dev))))
...
boot.user=> (start-repl)

and I'm not totally sure how to interpret that

[Malabarba]

I had a scheme that worked for this (with boot) back when I did a bit of cljs. I used the same library you're using. I'll try to dig it up.

As for trying to be smart, the best we can do is have a separate variable for boot and let the user decide what code gets run. Cljs repls are way too numerous (and quite a bit of manual) for us to provide a catch all solution. That's why we wrote that original lein-cljs-repl variable. We people instructions on how we know it can work, but we can't promise it will fit into every ad-hoc method out there.

[bbatsov]

I think @Malabarba is right - probably we need a boot-cljs-repl variable as well. @dpsutton if you'd like you can implement this - should be pretty straightforward.

[dpsutton]

I'm not sure that I really like the variables. With the current one for lein, I've run into issues. For instance, I set it to the one I most often use. I clone a project which uses a different repl type. My interaction isn't seamless. I try to use a directory local var but don't really know them that well.

I like when it works smoothly but it seems to commit you to a certain type of repl for all projects. But I agree it works for the most part. Thoughts?

[bbatsov]

I like when it works smoothly but it seems to commit you to a certain type of repl for all projects. But I agree it works for the most part. Thoughts?

Well, that's the Emacs way - you come up with some sensible defaults and use dir-local variables for projects that don't adhere to the defaults. I definitely don't want us to start inspecting the project files to figure out what would be the best way to start a cljs repl.

[arichiardi]

Ran into this problem and I can work around it by using the following .dir-locals.el:

((nil . ((cider-boot-parameters . "dev-web")
         (cider-cljs-lein-repl . "((eval 'adzerk.boot-cljs-repl/start-repl))"))))

Of course it would best to have a better name and defcustom for boot (and grandle?) builds.
I actually so like .dir-locals.el configuration, it is good because you can have different ones for each src subfolder: one for src/my-lein-prj and one for my-boot-prj.

[arichiardi]

On second read, it looks like the problem above is different, about the rename, the commit is this: 313a0df

And probably we should add a clause for adzerk.boot-cljs-repl/start-repl in there.

[arichiardi]

The problem with the template is exactly that it does not launch or even hints at boot-cljs-repl, see here: https://github.com/hoplon/hoplon-template/blob/master/src/leiningen/new/hoplon/build.boot

My dev-web task does:

(deftask dev-web []
  (init-web)
  (comp (serve)
        (watch)
        (cljs-devtools)
        (reload :client-opts {:debug true})
        (cljs-repl :nrepl-opts {:port 5088})
        (cljs :source-map true
              :optimizations :none
              :compiler-options {:external-config
                                 {:devtools/config {:features-to-install [:formatters :hints]
                                                    :fn-symbol "λ"
                                                    :print-config-overrides true}}})))

[arichiardi]

If we wanted to be really fancy here, we could inject [adzerk/boot-cljs-repl "0.3.3" :scope "test"] as dependency and then call the init as per above.

[arichiardi]

Actually, not solved, it is still calling the rhino repl:

org.mozilla.javascript.EcmaError: ReferenceError: "console" is not defined. (rhino.clj#41)