I was thinking more along the lines of lispyscript[1]. It's not as good as SPOCK[2], or clojurescript[3], but there's less overhead than clojurescript, and SPOCK is known to stretch your javascript implementation in odd ways.

1: http://lispyscript.com/

2: http://wiki.call-cc.org/eggref/4/spock

3: https://github.com/clojure/clojurescript

parenscript is quite low overhead; it's approximately lispyscript with common-lisp macros instead of whatever lispyscript has (it looks like some kind of pattern-matching style; there's only one macro example on the lispyscript documentation and the link to an article about more details is dead). In any event if you know lispyscript you can probably translate my code; it took me only a couple of hours to write the initial react version, and another 45 minutes or so to translate to mithril.