This is from a couple of weeks ago, there's a few things broken still, but what languages do have full support out of the box?

http://blog.honeybadger.io/ruby-s-unicode-support/

Perl6 https://perl6advent.wordpress.com/2015/12/07/day-7-unicode-p...

Swift

Go

Doesn't look like Go does: https://github.com/golang/go/issues/14820

Well, for one, I can't even write a portable unicode string literal.

> "\xAA".split ''

That works on a platform where my platform is UTF-32, but not one where it is UTF-8.