ramnathv/knitr — comment on commit bb08d1ca76fb9c8b8817edcfade5a1a8e9b861e7
File: R/highlight.R line 46
By yihui:

OK, that is what I guessed. It is indeed not a good practice to write multiple parentheses, and in R sometimes it is even dangerous due to lazy evaluation (I was bitten hard by this kind of bugs before but still feel tempting to write `f(g(h(a)))`...).