ElixirScript looks like it will be nice in time, although seems a bit awkward to use with JS libs. Can't wait to see how that matures!
I've been tinkering with an old language project RedScript to make it more functional (Elixir like). Just a toy though:
Also, +1 for LiveScript.
It's a powerful little language when combined with prelude:
http://learnxinyminutes.com/docs/livescript/
http://livescript.net/blog/10-things-you-didnt-know-livescri...
RedScript is more like CoffeeScript and ElixirScript is more like Elm/ClojureScript IMHO. It has little to no overhead overhead after transpiling however 2.0 will use seamless-immutable (via CommonJS) to help with copying data.
Here's the 1.0 before/after conversions: https://github.com/AdamBrodzinski/RedScript/blob/master/spec...
It still needs a proper compiler, this is basically using RegEx to match/replace (it was a project to learn RegEx). It's surprising how far it takes you. I've built a small web app with it and it works well. I don't trust the compiled output without testing though (due to the RegEx strategy).
I haven't had to the time to make the changes in the complier but shouldn't take more than a few beers and a weekend :)