On 11/18/2012 4:31 PM, Manu wrote:

If I told you this is how real should be implemented, would you vote ++? What
about double? Why?
Why not float for that matter? There seems like no reason for the language to
define any floating point type at all if you consider this acceptable...

Because they are implemented in hardware. It's pretty dang hard for a compiler to look at a floating point emulator and figure out "gee, I have a nice hardware instruction that does the same thing as this 2K of code!"

Right, and this is my point precisely. It's hard for GDC for instance to hook some complex library because it happens to have hardware to do it.

'half' isn't some custom float for niche use, it's an established standard,
implemented in vastly more hardware than implements 'real'.

It's implemented in GPUs, sure, but it is it implemented in hardware that D runs on? (I do know about this: http://gcc.gnu.org/onlinedocs/gcc/Half_002dPrecision.html)

There is no major technical difficulty in implementing it as a basic type, but I want to be sure we've exhausted the library approach first.

Well it's available in hardware on basically all mobile devices (that's a LOT of devices (in the billions)), but even if it's just implemented in software (x86), the values are consumed by the GPU, and the validity of the values is no less important. It still seems like a valuable 1st class type; why shouldn't it enjoy the same casting, assignment, literal, range checking rules as the rest of the floats? Additionally, convenience and compatibility with generic code would be significantly improved.

I don't see how it can be made to feel seamless with a lib... and that sounds like an awful lot more work.

Anyway, I'm not desperate for this personally. I just wondered how people felt about it in general, and if it was something that should/would be seriously considered.