You said you use "unless" in English as if that proved it was good to use it in boolean logic too. It doesn't. For example, I am happy to use !, &&, and || in my code, even though they aren't English. The criterion for what makes good code is different than what is good English.
My point was that I think an explicit not is clearer than unless in cases sufficiently complex as to require stopping to think about it. If you're trying to keep track of multiple negations, then having one be in a different form than all the rest does not help. (And meanwhile, there is nothing wrong with a habit of always using if).
"The criterion for what makes good code is different than what is good English."
In total, yes, but that does not mean that there are no things that work in English that also happen to work in code.
Furthermore, it is difficult to generalize about this: some programming languages are entirely unlike English and work very well, others attempt to be like English and are terrible, while others attempt to be like English in some ways and work.
And further to that, some parts of some programs attempt to be like English and work well, while other parts of programs work well when nothing like English.
Now while I understand bang, andand, and oror, they are a terrible legacy of our C++ days. Bang is especially unforgiveable. If we must have a prefix operator, what is wrong with ~, the actual standard symbol for negation?
;-)
p.s. This thread may seem to be a digression, but it seems quite pertinent to an article that talks about writing code for readability.
I agree with you that !, &&, || aren't the best idea ever. I wonder if the reason behind them over words is so you don't have to put spaces around them. Omitting spaces seems to be popular with the infix crowd (e.g., they happily give up *,+,- from identifiers just to leave out some spaces).
My point was that I think an explicit not is clearer than unless in cases sufficiently complex as to require stopping to think about it. If you're trying to keep track of multiple negations, then having one be in a different form than all the rest does not help. (And meanwhile, there is nothing wrong with a habit of always using if).