also i should mention that i hate java with the passion of a thousand burning suns 🙂 that part is not rational though

ha, sure

Well, you know clojurescript. So while you may never use it, you also have the power to do some serious thread thrashing in the future, if you want 🙂

in whatever domains clojure eventually lives on

the jvm is pretty good though

just as an example of what i mentioned before, take when i first started reading documentation on core.async so I could do some remote calls. the first thing any book or online resource will say is “go blocks run your process on a thread pool” or something like that. you know immediately that’s completely wrong, so you have a little bit of work to do to figure out what’s going on. there are often places like this where the most thorough sources are clojure oriented and so there’s a little friction. this is all i meant.

right but the problem there is the content

not core.async

Yeah, but Clojure is an abstraction. We may all be using it on some completely different host one day, where the thing isn't called a thread pool. Your point that there is friction in the docs as a result is true though

Rich specifically designed core.async (really through CSP) to be agnostic to the underlying threading model

but I see your point, older Clojure information (and thus more Google-able) is often missing the expanded context to include CLJS

at the last conj I actually had a very interesting conversation with Guy Steele

I tried to put him on the spot and I asked, "So, what's your favorite part about Clojure?"

He said that he believed that Clojure "got concurrency right."

The quadrants of coordinated/uncoordinated and synchronous/asynchronous

And how atoms, agents and refs answer each necessary quadrant in the "right way"

And that's pretty much the only thing I've ever heard Guy say that I've actually understood, so it must be right 😉

If you are interested in the upcoming ClojureScript 1.10.x a recorded talk on it is now available https://www.crowdcast.io/e/virtual-clojure-meetup-3

@mfikes you need to register?

I didn't register—I just went in with my Google account.

I think they have some sort of oauth setup with perhaps Facebook and other identity providers

what do I need to setup to use react-dom with advanced compilation?

I tried :infer-externs true and that didn't change the outcome, only added a compiler warning

(the warning is that goog is not defined in the externs)

looks like if I switch my call from react-dom/render to js/ReactDOM.render then the :infer-externs works ¯\(ツ)/¯

I wasn't going to share this because I was trying to figure it out myself but the error said to report it.

java.lang.IllegalStateException: EXPR_RESULT 35 [length: 3] [source_file: /Users/wade/Desktop/rn4w/node_modules/react-native-web/dist/vendor/Animated/AnimatedImplementation.js]
     java.lang.RuntimeException: INTERNAL COMPILER ERROR.
                                 Please report this problem.
                                 
                                 EXPR_RESULT 35 [length: 3] [source_file: /Users/wade/Desktop/rn4w/node_modules/react-native-web/dist/vendor/Animated/AnimatedImplementation.js]
                                   Node(NAME add): /Users/wade/Desktop/rn4w/node_modules/react-native-web/dist/vendor/Animated/AnimatedImplementation.js:35:4
                                 var add = function add(a, b) {
                                   Parent(VAR): /Users/wade/Desktop/rn4w/node_modules/react-native-web/dist/vendor/Animated/AnimatedImplementation.js:35:0
                                 var add = function add(a, b) {
                                 
     clojure.lang.ExceptionInfo: EXPR_RESULT 35 [length: 3] [source_file: /Users/wade/Desktop/rn4w/node_modules/react-native-web/dist/vendor/Animated/AnimatedImplementation.js]
    from: :boot-cljs

@grounded_sage That is an error in Closure compiling JavaScript in a Node module, not ClojureScript (https://github.com/google/closure-compiler/blob/4ea1570b891ed23395fa595362314a70b7295f90/src/com/google/javascript/jscomp/Compiler.java#L2861)

Ah I see @mfikes is this something I did wrong or because the Node ecosystem isn't quite there yet with the CLJS/Closure ecosystem?

For reference I am attempting to use the React Native for Web library.

I'm actually watching you Clojure meetup talk right now btw haha.

Dunno. But I suspect that a problem like that can be produced independently of ClojureScript, running the standalone Closure compiler against the offending JavaScript.

Ran the closure compiler against the directory and it worked

The error doesn't show when I don't require it into a namespace. So I believe it is something to do with requiring it into the namespace

Most likely an error on my end but I'm not sure what this could be. Not much written material about using NPM deps that I can find.

how do you interact with javascript callbacks when working in clojurescript?

if you for example have javascript like this

how do I interact with doc.on('end' ...) in order to retrieve that value in result when it is available?

(.on doc "data" #(.push chunks %)) ?

Hm. doto might work.

i'm trying to generate pdfs on a node server using macchiato

(doto doc (.on 'data' (fn …)) (.on 'end' (fn …)) (.end))

Does Buffer not have a constructor?

i might have to just leave the js as is and rather interact with the callback function from cljs

since this is all async operations, i can't just declare a buffer and then return it

(defn gb [] (let [buffer (Buffer.)] (doto doc …..) buffer))

need to return it in the (.on "end) call

Oh.

When doc.end returns, the buffer might still be “in process” somehow?

when doc.end triggers the printer is done writing data to the buffer

all that's left is concat it, convert it to a b64 string and return it

you return it in the “end” callback, so all you need is (.on doc "end" gb) where gb is the function @zentrope defined above

but i'm pretty new to all this stuff so I get confused easily 🙂

the Buffer. is the clojure syntax for new Buffer which may be confusing. i actually prefer to write (new Buffer)

Yeah, pass in a function that you call once the buffer is converted, or a channel (core.async).

oh yea it i suppose you might prefer to use a channel instead of mutating the chunks global. i’m not sure what exactly you want to accomplish. but either way that’s how you deal with js event callbacks.

essentially trying to convert that code I pasted to cljs, wrapping it in a function that will return the buffer in the end callback

trying out your suggestions now

I don’t think you can just return the value because the wrapping function will terminate before that value is produced.

So, you have to use a callback to get the value (or some such async method).

Using it would be like (get-me-the-buffer (fn [buffer] …)).

Then, in the callback, update your central state atom (if that’s what you’re doing).

i thought about using an atom, maybe that's just as easy

the atom is going to be the most straightforward translation because mutating a global is what the original pasted code does

i'm essentially trying to do this

https://github.com/bpampuch/pdfmake/blob/master/dev-playground/server.js

although it occurs to me that you probably want to mutate the javascript object itself

In a react-ish browser app, there’s usually a “state” atom from which the UI is generated. If you’re doing some sort of node thing, then … I don’t know.

yeah this is node, using macchiato to run cljs on a node server

Line 40, they’re using a callback.

i want to generate pdfs on a server and return them as a http/post response

figured i could wrap the response body as a readstream

wait a sec isn’t there a clojure native pdf maker

Line 48, they create a callback that then fixes up the response.

I think so, but it depends on JVM libs, doesn’t it?

i'm not aware of anything clojure-specific

https://github.com/clj-pdf/clj-pdf

it's an option, but i already have cljs code for generating the pdf with pdfmake

the thing is we're trying to move pdf generation from the client to a server

this is trivial in pure js as all you have to do is follow their examples with use a node express app and the node http server

in order to not have to interact with javascript i've been trying to write that createBinary function with cljs instead

but I guess another option is to keep that in js and wrap the callback in a go block

yeah, i you could just keep it in Javascript, and call it from within cljs

You might try shadow-cljs which (I think) keeps pretty close to the NPM ecosystem.

i've been trying macchiato, seems to work fine

https://github.com/macchiato-framework/

https://github.com/thheller/shadow-cljs

It’s a build system, not a replacement for macchiato

https://medium.com/@jiyinyiyong/a-beginner-guide-to-compile-clojurescript-with-shadow-cljs-26369190b786

oh, so you're trying to build a nodejs web server using cljs, with machiatto? You are also trying to talk to a PDF generation library, which is a dependency on npm?

That’s the picture I’ve gotten.

mm-hmm

yeah, shadow-cljs is probably the easiest way to pull in the dependency, and use machiatto

Theoretically, at that point you’re just doing a direct transliteration.

(def pdfmake (node/require "pdfmake"))

using cljs.nodejs works just fine on my local setup

@restenb that is the easiest way to pull in your dependency, but the builds tools have recently been including the ability to pull in npm dependencies to appear correctly in the cljs module system

ie. (require ["pdfmake" :as pdf])

oh

or in your ns-form, (ns (:require ["pdfmake" :as pdf])), etc

it's still a bit experimental, so using the node/require is your best bet for now

you can define :npm-dependencies with macchiato too i think, i haven't looked into that

oh?

idk, noticed something in project.clj

I thought macchiato was a web server resembling the ring-based clojure stuff, built in cljs for node?

ah, ok

you're using leiningen

yeah

:npm {:dependencies [[source-map-support "0.4.6"]]

this is in the default project.clj

shadow-cljs is an alternative to leiningen, which is purely cljs-based

the idea behind it was to provide a lower barrier of entry for people wanting to try out cljs, without requiring the buy-in of Java (with tools like leiningen, boot, clj, etc)

but if you're already at a point where you have your clojurescript compiling, than that's great

just make sure that you include your cljsbuild target as :nodejs, are you able to run your compiled code on node?

yes it all seems to work fine

the default macchiato setup even has figwheel

oh nice, yeah you should be set 🙂

the pdfmake stuff can be added in the :npm :dependencies area

you just call lein build and then node mystuff.js and you're set

Yeah. Just use the callback, exactly like that example code does.

and you should be able to node/require it without issues

don't think you necessarily need to include it there, you could always manage your own package.json with npm

it's just pulling the dependencies out of node_modules

i know the pdf generation itself works, but i want to avoid saving the pdf to disk before serving it

ah, so you want to store it as a bytearray?

You'll have to look at how Node handles those situations

and perform an interop within cljs

trying to generate it into a Buffer and then returning that as the response wrapped as a stream

got stuck on the buffer part

Isn’t that exactly what that code is doing?

yep

so i tried to translate that code to cljs

I'm not familiar with machiatto, but I know it follows closely to clojure ring-based servers. There should be a similar Ring Response object in machiatto with similar functions for assigning byte data to the response body

res.send(binary)

yeah i'm pretty you can just wrap it as a file in macchiato

(defn file "accepts a path to a file, and returns a response with the body set to the file stream." [path] {:status 200 :headers {} :body (fs/read-stream path)})

ah ok

since the body is a read-stream it shouldn't matter if it's a path or a buffer

Oh, so you DO want to save it to a file?

not on the server generating it, no

Does pdfmake generate a bytearray from it's generated pdf?

@benzap Look at: https://github.com/bpampuch/pdfmake/blob/master/dev-playground/server.js

yes, it's just a b64 string i think

I think that’s what he’s trying to do.

oh I see

hmm....

I don’t see why that doesn’t work as a straight translation into CLJS.

looks like you're going to deal with callback hell

yeah

you could just do a direct translation, and replace the express parts with machiatto

personally, i'd try and self-contain the generation in a core.async go block

that's why i was thinking about keeping the actual buffer generation as js, and then wrapping the callback from cljs with a go block instead of trying to translate it

all the power to you, I see nothing wrong with that

something like this should work

(go (let [c (chan 1)] (.generatePdf pdfDate (fn [err, res] (go (>! c res))) (<! c)))

although it looks pretty awkward at first glance

Oh, so you want to move that to a different framework. light dawns ;)

Could you make the function take a response object?

(defn gen-pdf [response] …. (response {:body buffer})) ?

@restenb similarly, you could return the channel c to a response, and pull out the data

Oh, right. You have to hand that response to something, rather than write to it. Ah, well.

if i have the buffer i can just do something like this i think

(defn get-pdf-response [req res raise] (-> (r/file (report/create-pdf report-data res)) (r/content-type "application/pdf") (res)))

`(defn generate-pdf [content] (let [success (chan 1) error (chan 1)] (go (>! success (heavy-lifting content))) [success error]))`

and have create-pdf be wrapped in a go block reutnring the buffer

then i tried doing it all from cljs and ran into problems implementing this

doc.on('end', function () { result = Buffer.concat(chunks); callback('data:application/pdf;base64,' + result.toString('base64')); });

as the buffer is what needs to be returned in the callback

Isn’t result.toString() the buffer?

Or did you want to do something different?

yes

Maybe call (.toString result), then return the buffer?

Assuming .toString resolves everything, even if you throw it away.

(.on "end"
     #(let [result (Buffer/concat chunks)]
        (callback result)))

That didn’t work?

the callback needs to be your response, or it needs to be where you pass your result into the channel

Maybe paste in your WIP. :)

messing with it. not that familiar with core.async either

so i'm keeping the chunks in a javascript object, it's just easier to work with javascript objects when working with javascript libraries

but essentially, this will process everything, and throw the result in the result channel, you can either pull from it with take!, which uses a callback, or you can grab the value from it within a go block with <!

(take! result (fn [chunks] ....)

yeah i was trying something like that

I guess the big issue is pulling the async result into machiatto, which i'm guessing uses callbacks

anyway, let me try and sew this together and see how it goes

hi, i am working on a demo involving moving code between a client with clojurescript and a server with clojure. what would be the simplest way to get going with a basic form and a few buttons in cljs? i've used om-next a bit and while it has some big wins it doesn't seem like the easiest solution. i want this to be easy.

any ideas?

i use reagent and re-frame for GUI with hiccup for HTML

https://github.com/Day8/re-frame

RUM is a nice alternative.

I wrote about how to serve ClojureScript files in development without running into weird caching issues: https://danielcompton.net/2018/03/21/how-to-serve-clojurescript

@danielcompton Cache-Control: max-age=0, no-cache, no-store, must-revalidate and skip everything else

etags seem like total overkill

You wouldn’t need all of those directives, your header would have the same effect as Cache-Control: no-store

I found a noticeable page load time boost from using ETags, because the browser didn’t need to re-download the file every time

during localhost development?

yep

On todoMVC with re-frame + re-frame-10x it went from 2.3s to 1.5-1.7s to reach DOMContentLoaded

Just compiling a real world app now for a comparison

hmm do you have the project somewhere so I can compare with my setup?

1.5s still seems pretty slow

yeah it’s a slow laptop

I'm curious how it would look with https://shadow-cljs.github.io/docs/UsersGuide.html#_async_loading

What is it about fetch that is better for loading lots of files?

async

by default the closure debug loader uses script tags. which means the browser must download and eval the code before continuing with the DOM

Why would waiting for DOM affect anything in this case as the code must be evaluated anyway before the app can do anything?

On our real world app, we get 10 second loads instead of 13 second loads

I think the next frontier for ClojureScript dev performance is HTTP2

shadow-cljs already has that 😉

because the browser will only open 6 requests per connection

Well for Figwheel then 🙂

and yes its pretty neat but configuring trusted SSL certs for dev is a nightmare

I’ll bet

The problem might be figwheel here. Last time I checked the import/reload code it loaded js files consecutively. It should instead just add all N js files as script tags and let the browser download them in parallel and then execute them consecutively

@rauh I think we are just talking about initial load here

Oh, I see

Yeah so then HTTP/2 will make a huge difference. I have it setup with openresty and it reduced it by like a factor of 3-4x IIRC

yeah its pretty good

@danielcompton I’ve never had this issue bc I always have DevTool open with cache disabled 🙂

Jup, 338 requests, 8.8MB transferred, Load: 1.44 seconds. It's super quick

@roman01la 🙈🙉

uhm no gzip? 🙂

151 requests, 896 KB transfered, finish 533ms, load 66ms

buts thats async in a dummy test project which doens't do much

280 reqs, 15.8 MB, 6s

I think gzip should help a bunch

No I found gzip/brotli slowed it down a bit, not by much but it's loopback so no reason for gzip I guess

I guess http2 and gzip can be done with figwheel via custom Ring handler?

gzip yes, http2 no. thats a server thing.

http-kit doesn't support http2 or ssl IIRC

If browser just supported h2c... that'd be so nice

Then getting Http/2 would be much simpler...

yeah ssl is the most annoying thing for http2 during dev

if you get the cert setup properly it works fine

but getting that setup is horrible

and immediately breaks if you want to access from a remove dev setup, ie. not localhost if the cert is localhost

Hi there, I couldn't find a solution on following problem: when running lein with-profile test doo phantom once phantom fails with

ReferenceError: Can't find variable: Map

   in onError
Error encountered performing task 'doo' with profile(s): 'dev,test,test'
Subprocess failed

Anyone has a hint on that?

You need to add a plus before your profile

lein with-profile +test doo phantom once

There is a new guide covering the ClojureScript ns form and all it has to offer: https://clojurescript.org/guides/ns-forms

@mfikes it doesn't mention (:require ["react-dom/server" :as x]) yet

@thheller Right, the original content was written back in early 2016, which I think was prior to string requires. Someone familiar with that feature should submit a PR covering it.

I'm getting inconsistent errors across build tools and it's got me very confused.

When I require react-native-web using NPM deps on Lumo it works fine. When I do it with Leiningen I get Undefined nameToPath for react_native_web then when I am using Boot I get an error from the GCC.

@thheller Expanding on that, there should probably be a guide covering NPM dependencies, if there isn't one.

well for that it first needs to work more reliably in CLJS

@grounded_sage I'd suggest you try shadow-cljs where this works much more reliably

Forgive my ignorance but what does shadow-cljs give me @thheller?

working npm deps for one? but also everything other build tool would give you

Ok cool I will definitely check it out. Can I use Figwheel etc with it?

no, but it provides everything figwheel would provide on its own

I wanted to try to run tests on every save with cljs.main. Here's where I'm at:

clj -A:test -m cljs.main -co "{:watch-fn lime.tests/-main}" --watch "test" -c

ClojureScript 1.10.217

@petterik Hrm. Perhaps that's the only compiler option with a non-edn value...

@petterik Perhaps it could be easily expanded to work like :preprocess in :foreign-libs (take a symbol that gets resolved to a function as in your example). I'd suggest an enhancement JIRA.

@mfikes I'm not familiar with :preprocess, but I can create a JIRA and include your comments?

@petterik Sure. Take a peek at :preprocess description here https://clojurescript.org/reference/compiler-options#foreign-libs

Cool, yeah, sounds good

It would seem easy to have the compiler check of :watch-fn's value is a symbol, and if so, conditionally behave like :preprocess does.

It'd be nice to be able to pass clojure code as well 😉

But taking a symbol works for my case at least

thanks

Yeah, cljs.main reads in compiler options as EDN right now.

am i missing a really obvious clojure.string/format function? i found format in an older cljs version, and also goog.string/format in an older gcc version

but both of them have changed; format is no longer in cljs.core, and it’s goog.string.format/format — what’s idiomatic?

@lwhorton Not saying its idiomatic, but format usage is documented here https://clojurescript.org/reference/google-closure-library#requiring-a-function

Alternatives are str, cljs.pprint/cl-format, Cuerdas

☝️ cuerdas was exactly what i was looking for!

Strange. I have an old app I’ve updated deps for and suddenly “vals” in CLJS doesn’t work.

There is a new reference page covering the stable JavaScript API exposed by the ClojureScript standard library: https://clojurescript.org/reference/javascript-api

@mfikes I’m slightly confused by that page. It says that “ClojureScript defines types that have stable, publicly-consumable JavaScript APIs” but then all of the examples are in clojurescript.

Is the idea that you can call .indexOf from javascript on a clojurescript vector?

Perhaps there is a better way to describe the concept...

The idea is that, any ClojureScript value satisfying the sequential? predicate also defines JavaScript functions as defined on that page. Thus you can reliably use JavaScript interop to call those functions without being in a position of calling private API.

Feel free to contribute to the page to clarify. https://clojurescript.org/community/contributing_site

An converse example: If you do (.-cnt [1 2]), then your code is in danger of potentially breaking.

I get it now. I’ll just submit a small patch. Feel free to ignore if you don’t like my wording.

Cool. By the way, I don't accept or reject the patches.

I'm a contributor just like you 🙂

Well I just mean I’ll offer my friendly suggestions however is best for you. 🙂

So @lee.justin.m you almost have me convinced to try shadow-cljs in my project, but is there a way to integrate it into the lein build? Or will I need 2 steps to build a project? It’s a jetty backend and a Reagent frontend.

@jmckitrick shadow-cljs is in most part a replacement for lein cljsbuild, less painful in the long run I'd say, shadow-cljs prevents gray hairs

@jmckitrick Yes it is pretty nice to manage everything with shadow, but you don’t have to. You can run shadow from lein and let lein deal with the cljs dependencies (you still deal with npm dependencies using normal tools and a package.json) https://shadow-cljs.github.io/docs/UsersGuide.html#Leiningen

I haven’t done the lein integration so you should hop into #shadow-cljs for help if you get stuck

btw to answer the question, you need 2 steps to build a project, with or without shadow-cljs given that you're useing clojure and clojurescript. I actually don't build the clojure, just start it with lein ring plugin, but you can and some recommend that you build clojure into a .jar and start it all with java -jar

I’d really miss the figwheel integration. Especially with cider.

you wouldn't miss that 😉

but cider is still bit more manual at this stage, you'd need to require nrepl yourself

Well, I get the hot-reloading, plus cider integration lets me jump around my code like regular clojure.

you get hot-reloading with shadow too. he’s got his own implementation that works great and gives you the heads up compiler errors and all that jazz

I saw them in the terminal, but not in the browser….

i don’t know about emacs, but now that i switched to cursive i get full integration (docstrings, jump-to-definition, etc.) so I know that shadow is at least capable of those things (doesn’t work with atom, sadly)

the "hud" was added into shadow like 1-2 months ago, maybe you should try it again?

I just built the project 5 minutes ago 😉

I installed shadow about a week ago.

maybe we should take this to #shadow-cljs but basically you get error that is printed in the terminal but not into the browser?

ok

correct