Casting MapResult

[John Colvin via Digitalmars-d-learn]

On Tuesday, 16 June 2015 at 13:06:58 UTC, jmh530 wrote:
> On Monday, 15 June 2015 at 22:40:31 UTC, Baz wrote:
>
>> Right, my bad. This one whould work:
>>
>> ---
>> float[] test(float[] x) {
>>     auto result = x.dup;
>>     result.each!((ref a) => (a = exp(a)));
>>     return result;
>> }
>> ---
>
> That works. Thanks.
>
> I did some benchmarking and found that map tended to be faster 
> than each. For some large arrays, it was exceptionally faster. 
> Perhaps it has to do with the extra copying in the each formula?
>
> I also did an alternative to each using foreach and they were 
> exactly the same speed.

Range based code is very dependant on aggressive optimisation to 
get good performance. DMD does a pretty bad/patchy job of this, 
LDC and and GDC will normally give you more consistently* fast 
code.

*consistent as in different implementations performing very 
similarly instead of seeing big differences like you have here.