Comment by kbp

> If you want precise names to offer as aliases to "first" and "rest", then I think ML-style "head" and "tail" are better names than "car" and "cdr".

I don't know what you mean by ML-style, as most ML-derived languages call car and cdr fst and snd; I don't know any that call them head and tail.

But aside from that: really? I think of head and tail as being basically synonymous with first and rest (every language I know of that has built-in head and tail functions, or that idiomatically uses head and tail or abbreviations for variable names, uses them to mean the first element, and the list beyond that element. I don't know any that use them for two parts of a 2-tuple). The left child of a binary tree node being the head and the right side being the tail makes no sense at all to me. Not that car and cdr shouldn't be aliased when they're being used that way, but reading as "element a" and "element b" is better to me than "head" and "tail" which are equally meaningless, but by having English names imply meaning.

Lisp offers (since the 70s) the aliases first and rest for when conses are being used as lists, and I think those are fine and should be used when you are operating on lists. Conses can be used as other things than lists, though, and first/rest (or head/tail) don't work as meaningful names for any usecase aside from lists. Head/tail are totally equivalent to first/rest to me and I don't really care which pair is used for naming the list-handling functions, but they're both bad sets of names for the cons handling functions.