Which D features to emphasize for academic review article

[F i L]

Andrei Alexandrescu wrote:
> [ ... ]
>
> Although this case is not about default values but about the 
> result of a computation (in this case 0.0/0.0), I think it 
> still reveals the usefulness of having a singular value in the 
> floating point realm.

My argument was never against the usefulness of NaN for 
debugging... only that it should be considered a debugging 
feature and explicitly defined, rather than intruding on 
convenience and consistency (with Int) by being the default.

I completely agree NaNs are important for debugging floating 
point math, in fact D's default-to-NaN has caught a couple of my 
construction mistakes before. The problem, is that this sort of 
construction mistake is bigger than just floating point and NaN. 
You can mis-set a variable, float or not, or you can not set an 
int when you should have.

So the question becomes not what benefit NaN is for debugging, 
but what a persons thought process is when creating/debugging 
code, and herein lies the heart of my qualm. In D we have a bit 
of a conceptual double standard within the number community. I 
have to remember these rules when I'm creating something, not 
just when I'm debugging it. As often as D may have caught a 
construction mistake specifically related to floats in my code, 
10x more so it's produced NaN's where I intended a number, 
because I forgot about the double standard when adding a field or 
creating a variable.

A C++ guy might not think twice about this because he's used to 
having to default values all the time (IDK, I'm not that guy), 
but to a C# guy, D's approach feels more like a regression, and 
that's a paper-cut on someone's opinion of the language.