Clojurians Log v2

I’m trying to switch from Cegdown (a Clojure wrapper for Java Pegdown) to https://github.com/vsch/flexmark-java (the Java library recommended to replace it). The relevant Java import looks like this: import com.vladsch.flexmark.html.HtmlRenderer; I can only get Flexmark to load in my dependencies, if I include “flexmark-all” as such: :dependencies [[com.vladsch.flexmark/flexmark-all "0.62.2"]] But I cannot figure out how to require it successfully in the relevant contexts. Here’s what I’m trying: (:require [com.vladsch.flexmark.html.HtmlRenderer :as md2]) Here’s the error I get: Could not locate com/vladsch/flexmark/html/HtmlRenderer__init.class, com/vladsch/flexmark/html/HtmlRenderer.clj or com/vladsch/flexmark/html/HtmlRenderer.cljc on classpath. Obviously, I’m missing how something here fits together.

com.vladsch.flexmark.html.HtmlRenderer is a java class. your ns should have an import declaration: (:import com.vladsch.flexmark.html.HtmlRenderer)

If you're not familiar with java interop, you may want to check out https://clojure.org/reference/java_interop

I've been using flexmark to render my blog posts. It's worked well for me. You can check out https://github.com/phronmophobic/blog/blob/master/src/blog/mdown.clj if you'd like to see an example of using flexmark from clojure. My code is not* well documented, but maybe you'll find the example useful.

How do I best create a backend API call to return edn from a ring backend (back to a clojurescript webapp)? Can I just put edn in the `:body` of a route? That gives me some errors. Do I wrap it in a string like `"{:test [\"test\"]}"`

@zackteo I searched for ring edn middleware and saw this: https://github.com/tailrecursion/ring-edn -- and in the examples it looks like they are just doing :body (pr-str data) (the library seems focused just on decoding EDN from the request body).

And I guess just calling pr-str on Clojure would produce EDN so maybe it is just that simple.

Perhaps a silly question but is edn not the standard that is used for a clojure stack?

(I've only ever dealt with sending/receiving JSON since I have a Clojure backend but our frontend is JS)

@zackteo Clojure has clojure.edn/read-string but there's no (`clojure.edn`) print-string because (`clojure.core`) pr-str does the job. I don't know what folks do for a MIME type when send EDN back to the browser?

I see I see! Yeap looks like it really is that simple read-string and pr-str

i have a list of lists [["bob" 17]..] and a record (defrecord person [name age]), question: how do i convert all items in the list to the record? map ->person ,,, doesn't seem to do it since it passes the whole list as an arg

(apply ->person data) will convert an individual vector.

so (map #(apply ->person %) list-of-lists) should do what you need @enrico.teterra

I've used edn for communication between front end and back end, but I used https://github.com/cognitect/transit-clj for serialization since that's what it's purpose is

It probably doesn't matter too much if you're not exchanging a lot of data

user=> (defrecord person [name age])
user.person
user=> (def list-of-lists [["Bob" 17] ["Sean" 58] ["Jay" 60]])
#'user/list-of-lists
user=> (map #(apply ->person %) list-of-lists)
(#user.person{:name "Bob", :age 17} #user.person{:name "Sean", :age 58} #user.person{:name "Jay", :age 60})
user=> 

When will you use transit tho? I know people also use https://github.com/dakrone/cheshire . But won't this only be used if say the frontend needs to receive JSON? :thinking_face:

I haven't used chesire. here's the rationale for transit: https://cognitect.com/blog/2014/7/22/transit

Thanks! But wow seems like a lot to take in

ahh i knew there was a simple way =) thanks Sean

read-string and pr-str work well too. It can be something to look into if you'd like to improve the edn serialization.

Working with hugsql in Calva, and CLJ-Kondo keeps giving me this error even though the docs for the function prove it wrong, has anyone encountered this and know how to fix it?

Resolved. I just deleted the .clj-kondo folder containing it’s cache and it seems to be fine now

FYI this is a perfectly reasonable channel to ask such questions, but if in future you have questions that might be specific to clj-kondo there is also a #clj-kondo channel that is likely to hit active users (and even its developer).

Thanks for that 🙂

The example code is the same as the previous question, I defined Inner class defmethod like this:

(defmethod j/from-java QueryReq$Aggregation [agg]
  (println "ac:"))

...so I want to turn a website that mainly serves html and also serves javascript... into a phone app. What's the state of the art in the clojureSphere for native apps?

@zaymon.a.fc the reason clj-kondo doesn’t know about this var is that is generated by some macro it doesn’t understand. You can configure clj-kondo to ignore these vars. If you delete the entire .clj-kondo dir with also the config in it you will get less information from it

I didn’t delete the config. Although the issue only happened with one specific var generated from the macro and not all of them, which was why I was confused.

After clearing the cache it worked and didn’t complain any more

Ok, I think it will start to complain again though after you have visited the hugsql related namespace since kondo thinks it knows all about the vars in that namespace. See this conversation on how to ignore this ns. https://clojurians.slack.com/archives/CHY97NXE2/p1612389637097500

Is it possible somehow to access the previous element in the map function (I guess I could use map-indexed and get)

one trick is to utilize map 's extra args:

(let [xs (range 5)]
  (map (fn [a b]
         [a b])
       xs (next xs)))
;; ([0 1] [1 2] [2 3] [3 4]) 

Ah.. yes because fn receives one element from each collection. neat.

thanks

Good morning everyone! I'll be livestreaming another coding challenge at 9:45 AM EST today if you'd like to join. Today's challenge comes from another Eric Normand newsletter, you can find it at the bottom of this blog post: https://purelyfunctional.tv/issues/purelyfunctional-tv-newsletter-409-3-stakeholders-model/ And here is the link to the livestream: https://www.twitch.tv/a_fry_ Have a nice Wednesday 🙂

I'm just finishing up a Reagent tutorial and we use Chrome's lighthouse to check performance. The tutorial shows him getting an 88% but I'm getting a 69% and it is saying it is because I haven't removed unused js. But we use Shadow CLJS and the tutorial says the release command compiles it using Google Closure to do DCE and tree shaking for us. The tutorial's lighthouse assessment doesn't give that "unused js" warning so not sure why I didn't get the performance benefit.

What tutorial are you doing?

Jacek Schae's Reagent Pro course. It's been great. I'm excited to move on to his other one's now too.

lighthouse to check performance... interesting... don't know what that is -- thanks for the keywerd

I have noticed that compiling into cljs has some "sweet spots" where sometimes everything lines up perfectly under the little surgical switchblades of the compiler and it: compiles very fast, and the size is very small. then you add one character or one variable and suddenly it takes the standard time and the file size is bigger by a lot... which is usually not a problem because it's still lightning fast, but yeah, it's weird that there are resonant nodes in the compile process but also not that weird.

Not sure if this is the place to ask, but I'm doing a little bit of research in order to ... not have to write a SPA, and I came across this: https://hotwire.dev/ Is there anything stopping me from using that with a Clojure back end producing HTML? Does anyone here have any experience with it?

You can use it with any backend.

Yeah Lighthouse is part of Chrome dev tools. Just right click on any webpage, click inspect, and it's the last tab. Pretty cool. The reagent site had great Accessibility, "Best Practices", and SEO score btw. Pretty cool as it doesn't seem we did anything purposely to get those good scores.

I'm just bummed at the bad performance rating even though tbh, I don't notice anything while I'm actually using the site.

try it on the slowest device you have

That's an interesting tool...

I've seen some people experiment with this. I think one of them was @arnout. @tatut also did related work to this.

https://twitter.com/functionalbytes/status/1358498277407211520

another conversation here: https://twitter.com/martensytema/status/1346364415034224641