Why does D not have generics?

[Ola Fosheim Grøstad]

On Saturday, 16 January 2021 at 08:45:23 UTC, Ola Fosheim Grøstad 
wrote:
> Maybe I am overlooking something... This is like 1-2 cycles.

I haven't tested, so I could be in error, but it seems like these 
two might work?

ulong x = floatingpoint double value;

1: x ^ ((0ULL - (x>>63)) | (1ULL<63))

or

2: x & (1ULL<63) ? ~x : x | (1ULL<63)


So basically in generic assembly:

1:  shift right, sub, or, xor  => 4 very fast ops

2:  tst, cmp, (neg / or) => 2 fast ops + 1 branch

If this works, then there is really no reason not to use 
ulong/uint for floating point keys, except -0.0 and 0.0 will be 
sorted, but that is desirable sometimes, so could be a plus as 
well. If people don't want that then they should normalize to 0.0 
before using the key.