Code speed

[Don]

Lars T. Kyllingstad wrote:
> Don wrote:
>> bearophile wrote:
>>> So far I've just given a light reading of the code. Notes:
>>
>>> - pow(x, 2) and sqrt(y) can be written as x ^^ 2 and y ^^ 0.5 (but 
>>> you have to import std.math anyway, because of a bug).
>>
>> That's not a bug. It's intentional. x ^^ y will probably always 
>> require import std.math, if y is a floating point number.
> 
> Really?  Why is that?  I find that kind of disappointing, I always 
> believed it to be a temporary solution.
> 
> I think the inconsistency with the other operators will make this a 
> major WTF for people new to the language.  Why should a^^b require an 
> explicit import while a*b doesn't?

Because pow() for floating point, when implemented properly, is a HUGE 
function, that ends up dragging almost all of std.math into the 
executable. And I think it's deceptive to do that silently.
To make it completely built-in, basically all of std.math would need to 
be moved into druntime. Feel free to try to change my mind, of course.

> If the language made it possible to overload operators using free 
> functions, I wouldn't mind if opBinary!"^^"(float, float) was 
> implemented in std.math.  The way it is now, it's a halfway built-in, 
> halfway library feature, and just seems halfway altogether.

You can expect the integration to become cleaner; still, it's a 
compromise. It was a big fight to get it into the language at all, and 
I've tried to minimize the cost of it. ^^ is basically syntax sugar, and 
the price you pay for the additional tiny bit of syntax sugar (avoiding 
import std.math) has an appalling cost-benefit ratio.

Raising to a float power is really a niche feature. Are there really 
many uses for ^^ of floats, where std.math isn't imported already (for 
example, where you don't even use abs()) ?