Is there a way to parametrize namespaces or dependencies? I am at the moment fiddeling around this to make code optionally core.async compatible, but leave it synchronous on the JVM.

So cljs and clj do different things @whilo? That sounds like reader conditionals. https://clojure.org/guides/reader_conditionals

I am heavily making use of reader conditionals, but this is about macro-expanding code differently depending on backend settings. Basically you can use core.async on both JVM and JS, but sync code on the JVM.

Hi all.... I ama but stuck on this one...

this works for me: (apply conj #{1 2 3} '(4 5 6 )) as expected...

but when the set is in an atom I can't do this (swap! atom-with-a-set-in-it apply conj '(4 5 6))

the I get an error: Wrong number of args (4) passed to: PersistentHashSet

Try (swap! atom-with-a-set (partial apply conj) ‘(4 5 6))

yes, that looks good... but why the partial as well?

What you have ends up being (apply a-set conj '(4 5 6))

(partial apply conj) returns a function that is is passed the set as its first parameter and your (4 5 6) as its second parameter

makes sense. thank you @osei.poku