Request translation into Perl

I'm testing something, and I'm stuck trying to write a Perl equivalent of this function because Perl's syntax is made of ugly, rudimentary, hack and fail. Could you please show me how to do this very simple thing in Perl?

function f($i = 1, $r = 17) {
    return --$r <= 0 ? null : array($i => f($i + 2, $r), $i + 1 => f($i + 3, $r));
}
Thanks!

>>20

You are incredibly stupid. HURR ANONYMOUS FUNCTIONS WHO USES THOSE. Maybe everyone who comes from a functional programming background. Maybe people who care about closures, maybe people who care about doing anything more complex than formatting some poor HTML. What do you think ruby is all about? Those blocks are basically anonymous functions.

Python guy: @_@ Irrelevant and pointless. This thread isn't about you. It is about how PHP users are ignorant about programming.