I played around with this a little last night, it worked well. https://raw.github.com/gist/2652377/e972d6040fd0ebf91da82b64...

Nice to see pl/v8 so quickly growing into one of those most mature PLs for Postgres. Soon it is up there with pl/perl. pl/python, and pl/pgsql.

Coffeescript is already everywhere because it compiles to Javascript, but more first party support for it is awesome!

I wonder how this handles errors, if it correctly reports the right line number or not.

It depends what sort of error it is and if it's a compilation error or a runtime error. If it's a runtime error, it tells you what function the error happened, but not necessarily where the error was. If it's a compilation error, it can tell you what line the error happened on.