I hate to jump in here, but I have to agree with kyle.

My understanding on map has always been apply a function to a list to return a new list. In some languages, there is also an apply which is meant to modify the list in place.

Since most of the places where I've seen map-like constructs (Lisp, Haskell, etc.) are functional languages. The only way they would work is by returning a new list.

Unfortunately, Perl's map has a behavior that combines map and apply, which confuses the conversation.