Exporting Source Blocks with Symbols

[Michael Gauland <mikelygee@gmail.com>]

I've become fond of using Greek symbols in my R code (mu, sigma, etc). R
handles these just fine, but most of them disappear in the listing when I
export to LaTeX (lower-case mu comes through OK). I think the basic problem
is the the listings package can't handle the characters. I've come across
some ideas for coping with this in LaTeX, but they involve modifying the
source (e.g., escaping the symbols to math mode). Of course if I do that, R
won't know what to do with the characters.

Any suggestions? Does babel provide any hooks for pre-processing source
blocks for export? I didn't find any, but I often miss what's right in front
of me (just ask my wife!).

Kind Regards,
Michael Gauland