Great find Bill!

I missed this when desperately tuning my Game of Life simulation for extra speed (which uses way more bit operations than any Perl program I've ever written) -- back then, I just tried use integer, found it was a bit faster, all tests still passed... so just moved on. Should have carefully read the docs like you. :)

Update: See also: Re^4: How to test for empty hash? (where use integer fixed a bug with the inchworm secret operator ~~$#foo)