On Sunday, 21 February 2016 at 14:32:15 UTC, dextorious wrote:
Now, seeing as how my experience writing D is literally a few hours, is there anything I did blatantly wrong? Did I miss any optimizations? Most importantly, can the elegant operator chaining style be generally made as fast as the explicit loops we've all been writing for decades?
First off, you should really be using GDC or LDC if you want speed. On how to do that, see my blog post about here: http://jackstouffer.com/blog/nd_slice.html. Specifically the section titled "Getting Hands On".
Secondly, both of your other sum examples use naive element by element summation rather than the more accurate pairwise summation which sum uses with random access floating point ranges. So your not really comparing apples to apples here.
Since Phobos' pairwise summation is recursive, it's very likely that DMD isn't doing all the optimizations that LDC or GDC can, such as inlining or tail call optimizations. I haven't compiled your code so I can't check myself.
Also, templates are auto attributed, so there's no reason to include @safe nothrow, etc. on templated functions.
