Clojurians Log v2

I'm trying to set a custom error handler in the browser... but setting window.onerror doesn't seem to take effect right away. Does anyone know why? Here are two cases:

(defn error-handler [message url line column e]
  (js/console.log "MY CUSTOM ERROR MESSAGE")
  (js/console.error e)
  true)

(set! (.-onerror js/window) error-handler)

(defn fail []
  (throw (ex-info "Big error" {})))

(fail) ;; error-handler is not run.

But delaying the call to fail with setTimeout produces the expected result:

(defn error-handler [message url line column e]
  (js/console.log "MY CUSTOM ERROR MESSAGE")
  (js/console.error e)
  true)

(set! (.-onerror js/window) error-handler)

(defn fail []
  (throw (ex-info "Big error" {})))

(.setTimeout js/window fail 3) ;; error-handler is run!

It works for me just fine without setTimeout. No idea why it would work for you differently. BTW you can use js/setTimeout instead of (.setTimeout js/window ...).

Huh, but if I try the analogous JS code in a JS console I get the behavior that you see for some reason:

window.onerror = (message,url,line,column,e) => {console.log('my handler'); console.error(e);}

throw new Error('hi')
// Uncaught Error: hi

setTimeout(() => {throw new Error('hi')}, 0)
// my handler
// Uncaught Error: hi

Thanks for the tip about setTimeout. I have no idea what's going on either... but glad I'm not crazy.

Well at least there's an explanation for what I see in JS: https://stackoverflow.com/a/17534068/564509 Also the comments are interesting - try using (js-debugger) to see the call trace.

How/where in source code is persistent data structure implemented in clojurescipt? I’ve tried cljs website faqs and googling and neither showed in-depth explanations. Any pointers are appreciated!

you can see the implementation of clojurescript's persistenthashmap here: https://github.com/clojure/clojurescript/blob/master/src/main/cljs/cljs/core.cljs#L7879

Thanks!

you're welcome. it can be pretty dense at first

Also do I understand correctly that much more of cljs in implemented in itself than Clojure? That’s the feeling I got from skimming the cljs.core namespace, where I can see a lot of language feature protocols are defined, whereas in the Clojure counterpart they are in Java

and this can be helpful

https://hypirion.com/musings/understanding-persistent-vector-pt-1

yeah Rich Hickey (the creator) wrote about this in the history of clojure paper (which is an excellent read). Clojurescript is a "clojure in clojure" kinda language that he felt really demonstrated how good the choices made in the language was

ya I’ve read that one, was always wondering to what degree is clojurescript “written in itself” thanks a lot for pointing me to the source code, it explains a lot

ah ok. then i won't keep sending screenshots. sorry about that 🙂

yeah no nasty interfaces in clojurescript. you get to see the protocols

lol no worries, love your enthusiasm

Is there a reason that clojure every is not defined in clojurescript?

Clojure 1.10.1
user=> every
Syntax error compiling at (REPL:0:0).
Unable to resolve symbol: every in this context

you mean every?

whoops. i got the wrong clojure every

Pardon my cljs newbness, but I'm trying to make sure that all the members of set-a are in set-b. every? is not the answer. I then thought of subset from clj but it's not in cljs. Am I missing something?

Do you mean this function? clojure.set/subset?

yes

is that in the cljs clojure.core? It's not listed in the API docs

ah, but i see it in the source

It’s in set namespace

yes, just as it is in clj, but it's not listed in https://cljs.github.io/api/ which confused me

I see it https://cljs.github.io/api/clojure.set/#subsetQMARK

as i said above, once i thought to look in the source, i saw it. thank you for responding

Can I completely disable any optimizations the google closure compiler does to a single npm-dependency when using shadow-cljs? It somehow destroys a function call inside a web worker, and it seems I don't have any other options left right now

I’m not sure I understand your issue, but is it something you could resolve by downloading the source to your npm dependency and building it locally?

Well my issue is a bit weird, but here are the details: I use a library that converts a function to a string, so it can instantiate a web-worker: https://github.com/antvis/Graphin/blob/a87b8f64e2303aad42c94a72d2dd861e1a7ea234/packages/graphin/src/layout/basic/forceWithWorker.ts#L70 What happens is, that this function here: https://github.com/antvis/Graphin/blob/a87b8f64e2303aad42c94a72d2dd861e1a7ea234/packages/graphin/src/layout/basic/worker.ts#L6 Gets converted/compiled to the following code:

(... Some other stuff);function(){onmessage=...

I've tried it with webpack in a typescript project and can't replicate the issue there. In my clj project I've also played around with externs, reducing compiler-optimizations, etc. but to no avail. Therefore I came to the conclusion that something else in the closure compiler must be the issue, but I can't figure it out

@rob703 it appears the library does some runtime eval so it is likely that it calls something that was renamed and not expecting it to be minified/renamed. hard to say but there is no way to disable optimizations

But maybe it's possible to at least add some externs for the stuff that eval expects to be there.

I thought the same about externs, but since it's an anonymous function there's not much to do in term of named externs. Anyway, thanks guys! I'll try to figure something out, it may just end up as yet another workaround. Maybe I compile it separately and load it on app start or something like that

barebones hot reload: what are people using these days?

figwheel-main is pretty minimal.

kind of where i was headed, thanks

i briefly had the “well, a filesystem watcher that calls a build script…” thought

and then thought better of it

There's a little more to it annoyingly :)

I think you could make a lighter figwheel, but nobody really wants to! (it's a lot of work)