I would imagine Brandon Bloom's response to a similar question in the Clojure group is applicable to the ClojureScript implementation of of core.async:
https://groups.google.com/forum/#!searchin/clojure/close$20channel/clojure/Zr1FmmE2cpQ/F6m9Ye_n1VoJ -- Note that posts from new members are moderated - please be patient with your first post. --- You received this message because you are subscribed to the Google Groups "ClojureScript" group. To unsubscribe from this group and stop receiving emails from it, send an email to clojurescript+unsubscr...@googlegroups.com. To post to this group, send email to clojurescript@googlegroups.com. Visit this group at http://groups.google.com/group/clojurescript.
