Clojurians Log v2

Is there any recommended Java runtime/version for CLJS? I installed openjdk-16-jre-headless, I'm on Ubuntu. Running yarn build with shadow-cljs takes 65.12s user 1.44s system 99% cpu 1:06.97 total. Is that normal? It's a hello world app, generated by yarn create cljs-app, the react-start-app alternative for CLJS if I understand it correctly. And I'm running out of memory with yarn start pretty much immediately. OK, my server is very basic, it's an AWS EC2 free micro instance, so it's got only 1 GB of RAM. I added additional 2.5 GB of swap, but it'd cause exception saying it run out of memory without touching the swap much. And there's NOTHING else running on it. That feels weird to me. Is it really THAT slow or is it just OpenJDK? Should I be using different Java?

you can tweak the memory by setting :jvm-opts ["-Xmx700m"] in shadow-cljs.edn (max 700mb of ram). build times pretty much depend on what you are building and it should only be that slow once. after that the cache should kick in and make things much faster.

you can go lower with memory settings but going too low can make things slower. 500m is usually fine

Is there a linter for ensuring that each ns having deftests is included in a given project's cljs.test/run-tests call? Have always wanted that

Absolute beginner here, first day with ClojureScript. Stuck on this

(= 25 ((fn [n] (* n n) 5))

I would think it’s more:

(= 25 (#(% 5)   (fn [n] (* n n))))

The question is looking for a function that takes a function as an argument…

That's the answer, but the syntax is mind-bending. I understand # declares a function and % is a placeholder. 5 is the argument?

i've been doing clojure/script for quite some time and that is a very confusing question. and i don't really see any benefit to it

I discovered Clojure/script last night from a job posting for a position at Roam Research

I love the product and thought it would be nice to learn to language they use

5 is the argument passed to the function subbed in for % , namely (fn [n] (* n n)). So... yes. But it's not an argument of #(% 5) (a.k.a. (fn [f] (f 5))), just a hardcoded value.

Thank you guys!

The question is just trying to show you can pass a function as an argument… but it certainly is done in a confusing way. 🙂 It might have made more sense to provide the #(% %), and have the user create any function to pass in that satisfies the answer 25.

I know that this has been explained, but I feel like I want to explain it differently… Talking about arguments for functions may make it unclear that there are multiple levels of function call, and different arguments at each level. That’s adding complexity over the actual task, making it much less clear. Abstracting it down, it comes to: (answer (fn [n] (* n n))) Where the value of answer is what we’re looking for. This says that answer takes a single argument, and it’s the function that’s defined. When looking at the correct answer: #(% 5) I’d rather use the long form to explain, so an equivalent is: (fn [f] (f 5)) This is an anonymous function that takes another function and uses it on the number 5. We know that the answer is 25, and the function being provided is a squaring function, so that’s how we know that we want to apply to 5. The final expression is: ((fn [f] (f 5)) (fn [n] (* n n))) What a mess. What it says is: • calculate the first expression to obtain a function that takes a function and applies it to 5 • calculate the second expression to obtain a function that takes a number and squares it • calculate the result of applying the first expression (which evaluated as a function) to the second expression (which also evaluated as a function) That’s a lot for one expression. Not difficult when you’re used to it, but really tough for someone who is new to the ideas

I think your explanation adds a LOT of value, thanks! :thumbsup:

Thank you