Why is D slower than LuaJIT?

[Simen kjaeraas]

spir <denis.spir at gmail.com> wrote:

> On Wed, 22 Dec 2010 23:22:56 -0600
> Andrei Alexandrescu <SeeWebsiteForEmail at erdani.org> wrote:
>
>> I'm thinking what to do about iota, which has good features but exacts
>> too much cost on tight loop performance. One solution would be to define
>> iota to be the simple, forward range that I defined as Iota2 in my
>> previous post. Then, we need a different name for the full-fledged iota
>> (random-access, has known length, iterates through the same numbers
>> forward and backward etc). Ideas?
>
> I would keep length and add an opIn: if (e in interval) {...}. (I'm  
> unsure whether it's worth allowing different types for bounds and/or for  
> step; I'd rather make things simple.) Then, you could call it Interval,  
> what do you think?
>
> Note: The result would be very similar to python (x)ranges. D has a  
> notation for a slightly narrower notion: '..'. Thus, what about:
> 	Interval!int interval = 1..9;
> or else:
> 	auto interval = Interval!int(1..9);
> ?
>
> What kind of thingie does "i..j" actually construct as of now?

Nothing. The syntax only works in foreach and opSlice.

However, this works:

final abstract class Intervals {
     struct Interval( T ) {
         T start, end;
     }
     static Interval!T opSlice( T )( T start, T end ) {
         return Interval!T( start, end );
     }
}

auto intInterval = Intervals[1..2];
auto stringInterval = Intervals["foo".."bar"];



-- 
Simen