> In programming language design, one of the standard problems is that the language grows so complex that nobody can understand it. One of the little experiments I tried was asking people about the rules for unsigned arithmetic in C. It turns out nobody understands how unsigned arithmetic in C works. There are a few obvious things that people understand, but many people don't understand it.
Although even if there somehow are hard questions, I'm not sure understanding unsigned arithmetic would have helped whoever wrote that code. Because I think if you asked that person "what does this unsigned type do with -5 C?" the answer would have been pretty obvious.
I have been coding since the mid-80's and I wouldn't definitely assert that I know it well, without having a look into ISO C standard and the semantic expectations of the abstract C machine and implementation specific behaviors.
This might have been a factor here, given that most of Gosling's peers back then were probably still more familiar with K&R C and its different set of conversion rules.
But more subtle when you have: a.size() - 1 < len