Comment by adrian_b

Actually not all those are ancient customs, and not all that Janet uses is newer.

In the first description of the language LISP, from March 1959 (AIM-008), John McCarthy had used the names "first" and "rest", instead of what later will be called "CAR" and "CDR".

The names of "CAR" and "CDR" appear to have come from the students who worked at the practical implementation of the LISP interpreter on an IBM 704, and unfortunately we have remained stuck with them, like also with other features that were intended only for a temporary use, until being replaced in the "final version" (which was abandoned).