PureScript may soon be a serious contender in the HKT language category. It is more or less a strict Haskell for JavaScript runtimes with some new type system features like row types and more fine-grained control over I/O (see http://www.purescript.org/learn/eff/ and https://github.com/purescript/purescript/wiki/Differences-fr...). It has an experimental native (via C++11) backend.
What are the alternatives? I couldn't live without HKT these days (once you're used to thinking in them it's painful to work without them), which rules out most languages even in the ML space, and Scala has better IDE support than anything that's left (indeed an excellent tool ecosystem in general in terms of e.g. profilers, instrumentation) except possibly Ceylon (which doesn't have anything like the library/developer ecosystem of Scala). Even assuming Ocaml lands their modular implicits functionality doesn't change this as far as I can see.
Haskell is an option, but eager evaluation makes reasoning about performance much easier. (And I do think there are legitimate use cases for traditional OO inheritance, though this is debatable). If and when Idris reaches a similar level of library/tool support to Scala then it might become a better alternative to Scala Native, but not that many people are willing to use Idris in production yet.