I don't understand most programmers' aversion to functional languages. Yeah, it's tough to do at first, but so is every othdr paradigm. This article is pretty terrible if you ask me.
Interesting read, also references Scala: http://guidewiredevelopment.wordpress.com/2012/02/27/what-differentiates-gosu-from-other-languages/
Their 'open type system' sounds like type providers to me, as I understand them from http://scalamacros.org/usecases/type-providers.html. Sounds pretty cool.