I find NaN mostly awkward and annoying in practice. Writing graphics code, you often find that some rendering step just fails completely, and it's because you h

I find NaN mostly awkward and annoying in practice. Writing graphics code, you often find that some rendering step just fails completely, and it's because you had a NaN (almost always divide by zero) somewhere along the line. Trying to pin down exactly where it occurs can be a real pain. Rather than silently passing NaN along, it would be much more useful to fail immediately and loudly. Therefore, I'd be very wary of using this pattern elsewhere, unless you can carry along a backtrace to help track down the culprit. On the other hand, it is useful that GL shaders will still sorta-kinda work even if you have zero divides, rather than completely blowing up. In many cases this only happens on a single pixel with very specific inputs, and you can just ignore it -- like having a single dead pixel on a monitor.