As an ex-Scala developer I feel like Scala is also the worst language in this regard, even compared to more academic languages. At least Haskell is somewhat prescriptive; in Scala people continually invent new ways to do the same thing. How many iterations of dependency injection or IO are we at now?
Ruby is another language where I wouldn't want an unrestrained/undisciplined amount of smart/clever code.
My impression of Scala from a few years ago was that the language itself was so flexible (ranging from 'not quite Java' to 'not quite Haskell'), that you'd really want strict adherence to a particular style (or set of features) for a codebase to have hope of being maintainable.
I love and hate ruby for this reason. I'm working in it now, and it does allow some really fast-to-ship coding, but some of the LargeBrainedOne's framework stuff is so weirdly overly abstracted and metaprogramming'd ...
They'll write 500 lines of inscrutable framework code to save having to write 5 lines of boilerplate 3 or 4 times.
