I was recently attempting to implement an algorithm for continued fractions, in which the subscript of the variables was negative. It occurred to me that it might be convenient to fudge the index to make the implementation easier for me.

(Un)fortunately, I didn't know about $[, so I was compelled to actually understand the algorithm and write code so that Perl would be happy.

I think this is something like the Perl philosophy, not constraining people to follow a particular path. It's nice to know I *could* move the index, if I wanted to - even though I understand that if I ever did that, I'd likely be sorry...