Actually, it's more of "how many non-functional programmers who don't know what a closure is". Or, as a friend of mine put it, "Perl lets you do everything you'd want to do that LISP does, but without making it look like the language is hacked."
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.
Please remember that I'm crufty and crochety. All opinions are purely mine and all code is untested, unless otherwise specified.