Learning functional programming with R

I have recently studied functional programming with Haskell and
Clojure and found it has also improved my R coding practices. For
example I've better grasped the possibilities of usign lists and apply
family of functions instead of loops. As a side effect I also
discovered that a lot of my problems are parallel (and I can use
mclapply for significant speed up), but I've been
thinking sequentially in terms of loops.

I've read quite a bit of R material over the past couple of years and
although the benefits of using the apply functions is usually
demonstrated, I've found that still most of the examples
use loops instead of lapply, mapply etc.

Now my question is: Can you recommend me some good R tutorials or
books that have special focus on functional programming with R? If
such resources exists I'd like to recommend those for my students when
learning R.