[bcj]

I would say fn and mod are a lot better than cdr and car. At least fn and mod are just abbreviations of the words they represent.

cdr and car requires me to know 60-year-old implementation details of Lisp.

[kyllo]

This is why I like 'head'/'hd' and 'tail'/'tl' from ML/Haskell family more than Lisp/Scheme family's car/cdr.