http://www.quora.com/Why-is-Asana-developing-their-own-progr...
To quote:
Update: For the last few months, Asana has moved from
writing Lunascript for our application code to Javascript.
The two main things that were slowing down our development:
too much remaining research-level work to make the compiler
output more performant code
lack of tool support
We're *not* a framework company, so we didn't want to devote
years to this work at the expense of building our product. We're
still using the framework primitives we developed for the
language -- most importantly, systems for reactively recomputing
our UI and synchronizing changes with the server -- we're just no
longer using the slightly nicer syntax (and functional style)
that Lunascript provided.
Long term, we may revive the Lunascript compiler. We think this
may be especially appealing once we shift from focusing Asana as
a single product to Asana as a platform. But for the immediate
future, we're focused on releasing our first product at the
expense of continuing work on Lunascript proper.