Implement juxt

[anonimitoraf]

Fun project!

I've added an implementation for juxt. I'm a bit inexperienced with macros so completely open to feedback

Basic examples I tested with:

((lambda
   (&rest xs)
   (mapcar
     (lambda (f) (apply f xs))
     '(- +)))
  1 2) ;; => (-1 3)

((lambda
   (&rest xs)
   (mapcar
     (lambda (f) (apply f xs))
     '(1+ 1-)))
  1) ;; => (2 0)

[anonimitoraf]

Actually, how do I go about testing this E2E?

[borkdude]

There's currently no tests. If you feel like working on that, that could be very useful to this project.

For a possible test setup you could look at:

https://github.com/borkdude/flycheck-clj-kondo

Instead of emitting an inline definition of juxt perhaps we could emit a top level function which is then re-used?

[anonimitoraf]

Thanks, I'll check out clj-kondo.

When you say top-level fn, do you mean implementing defn?

[borkdude]

I mean, we can emit this first:

(defun juxt ...)

and then we just leave the call to juxt in where it was

[anonimitoraf]

Sorry, not sure I follow. Clarifying, did you mean to generate:

(defun juxt (&rest fns)
   (&rest xs)
   (mapcar
     (lambda (f) (apply f xs))
     fns))

and reuse this fn for subsequent calls?

[borkdude]

exactly :)

[anonimitoraf]

What's the best way to check if juxt is already defined (so that it could be reused?)

[borkdude]

We can keep that as state in the global context. But feel free to skip this requirement and continue with the inline implementation, I can take care of that part :)

[borkdude]

If you're trying to install babashka in Github actions, I recommend using the https://github.com/DeLaGuardo/setup-clojure action. It's much faster than brew.

[borkdude]

Similarly for Windows: there is no need to use scoop: setup-clojure works on all OSes.

[anonimitoraf]

I keep getting this error from eldev:

               signal(void-variable (/bin/sh:))
               apply(signal (void-variable (/bin/sh:)))
               (setq value-257 (apply fn-255 args-256))
               (unwind-protect (setq value-257 (apply fn-255 args-256)) (setq form-description-259 (nconc (list '(should (equal (clj2el-clj! ...) '...))) (list :form (cons fn-255 args-256)) (if (eql value-257 'ert-form-evaluation-aborted-258) nil (list :value value-257)) (let ((-explainer- (and (symbolp ...) (get ... ...)))) (if -explainer- (progn (list :explanation (apply -explainer- args-256))))))) (ert--signal-should-execution form-description-259))

Any ideas?

[borkdude]

Doesn't ring a bell. Maybe we can split up the PR to get CI working from the PR that adds juxt?

[borkdude]

No never mind, the juxt change seems small enough to this together. Perhaps you can compare what happens in the flycheck-clj-kondo CI compared to here? I'll re-trigger its CI to see if everything is still working over there.

[borkdude]

Just checked and flycheck-clj-kondo runs fine: borkdude/flycheck-clj-kondo@4c7a6c4

Perhaps @ikappaki has some ideas why this PR is failing

[anonimitoraf]

Thanks for the info @borkdude . Upon close inspection, it may have been because I forgot to install clj2el as an "executable".

Now that I do (via bbin), I get this error:

----- Error --------------------------------------------------------------------
Type:     java.lang.Exception
Message:  Could not find namespace: clojure.spec.alpha.
Location: /usr/local/bin/bbin:32:3

----- Context ------------------------------------------------------------------
28:   (upgrade [script])
29:   (uninstall [script]))
30: 
31: (ns babashka.bbin.specs
32:   (:require [clojure.spec.alpha :as s]))
      ^--- Could not find namespace: clojure.spec.alpha.

[borkdude]

Try to use a newer version of babashka

[anonimitoraf]

Cool, CI passes now. I do have one question though, in a case like this:

(clj2el-clj! (let [fns (juxt + -)]
                  (funcall fns 0 1 2 3 4 5)))

funcall is required (in elisp). Is there a way to get clj2el to insert funcalls when needed?

[borkdude]

Great!

Yes, I think we keep track if something is a local, so whenever a local is called, we can insert a funcall

[anonimitoraf]

Actually, I think we also need to cover the case of something like:

(def fns (juxt ...))

So on second thought, could we just add a funcall for every fn call?

[borkdude]

Let's take it issue by issue. Please wrap up the work that this issue was originally about and then we can address the next problem in a separate issue, else it's getting unwieldy :)

[anonimitoraf]

Ah yep, will do

[anonimitoraf]

Ok, I've removed windows from the OS matrix for now (having trouble getting bbin setup).

I think the rest of the stuff's ready for review

[borkdude]

@anonimitoraf Thanks a lot, excellent first PR!

[ikappaki]

Just checked and flycheck-clj-kondo runs fine: borkdude/flycheck-clj-kondo@4c7a6c4

Perhaps @ikappaki has some ideas why this PR is failing

Hi, I've addressed the ms-win failrue with #6, thanks.