I think Perl 6's killer feature is actually concurrency. P6 provides a number of ways to do reactive programming, channels, actor model semantics, etc. It even offers some new ways to approach modeling concurrency and asynchronous logic.

Here's a quick intro to supplies: http://perl6advent.wordpress.com/2013/12/19/perl-6-supplies-...

Here's a more in depth exploration of Perl 6's concurrency features: http://jnthn.net/papers/2014-nlpw-reactive.pdf

If you want to use a dynamic language (albeit also offering optional static typing) with powerful concurrency options that doesn't also involve s-expressions, I think P6 might be one of the few options available. I'm not familiar with Ruby, but from what I've heard the default runtime has some limitations when it comes to concurrency, and while it's been a while since I used Python, I recall hearing that it also has some problems with handling concurrency.