Successively prepending to slices.

[dnspies]

On Wednesday, 9 April 2014 at 23:43:27 UTC, bearophile wrote:
> dnspies:
>
>> efficiently, or is it better to avoid this sort of thing?
>
> D arrays are dynamic on the right. So appending on their left 
> is not efficient (also here you are not prepending, you are 
> concatenating. Array concatenation creates a new array). In 
> some cases you can append on the right many items and then use 
> std.algorithm.reverse (don't forget the () if you use UFCS) to 
> reverse them. In case of doubt write little benchmarks.
>
> Bye,
> bearophile

Does concatenation always create a new array?  What if the type 
of the original is immutable (or even const)?  In that case, 
wouldn't it be worthwhile to check first if rhs can be copied to 
the right of lhs?