I'm curious if ClojureScript uses the original clojure library code (eg, drop, take, map...) or re-implements them? I tried to find something in codebase, seems like it uses original.
A non-trivial portion of Clojure (data structures, compiler) are written in Java. In ClojureScript these are written in Clojure or ClojureScript so there's really not as much to share as it would seem.