in reply to mapcar -- map for more than one list

Some coding style questions:
  1. Why do you use if (! ...) and not unless (...)?
  2. Why do you use require and not use?
  3. Why didn't you extract out the common parts of mapcar() and mapcaru() and call some other function? Was it speed issues? (This would indicate we need a #define in Perl...)

We are the carpenters and bricklayers of the Information Age.

Don't go borrowing trouble. For programmers, this means Worry only about what you need to implement.