got the clojurescript compilation working, I'm an idiot:

node -e "var x = require('./cljs-output'); x.main();"
6
Eval
 [[:lambda [:x :y] [:cons :y :x]] :a :b] 
in environment
 [[:a [:m :n]] [:b (car x)] [:n :nil] [:c (quote m)] [:c (rest x)]] 
=>
 [(car x) [:m :n]]
6

did have to rename the file from "5.clj" though as shadow-cljs expects valid symbols as namespaces, and to match the file path