[schukin]

You probably shouldn't use 'nil' to mean 'false', but since pretty much every compiler / interpreter out there will take the same branch when given a condition that's either nil or false, I'd say it's much safer to stick w/ what's existed for decades rather than accommodate some sort of tri-state boolean.

[Confusion]

Well, the tri-state boolean was a worst-case, but consistent, example. I did mention you should hardly ever need that ;)