I'm sorry but this is possibly one of the worst comments I've seen... There is a conservation of complexity that you just can't get rid of in an application. To suggest that Scala encourages small programs, you are also suggesting that Scala is only appropriate for small problems, and thus it isn't a scalable language.

See: http://c2.com/cgi/wiki?ConservationOfComplexity

Ultimately, the baseline requirements drive the minimal complexity of code. Sure a poor programmer can drive up the complexity with unnecessary constructs, but the converse is not true: a great programmer can drive to simplicity. For example, a flight control system for a 777 can never be reduced to a single file of 700 lines of code. It will likely always be 2000+ files, and have lots of inter-dependencies.

So I guess (run time safety issues of Scala aside) Scala is not an appropriate language for complex problems by your own words?