In terms of functional languages for data science, surprised that Julia (http://julialang.org/) was not mentioned.

In terms of the R discussion, "Evaluating the Design of the R Language" seems to put the functional aspects in relief (http://r.cs.purdue.edu/pub/ecoop12.pdf)

In terms of where things are headed, I just came across Spivak and Wisnesky's work on Functional Query Language (FQL), http://wisnesky.net/fql.html. The introductory slides http://www.categoricaldata.net/doc/introSlides.pdf call to be read seriously.