What features of D are you using now which you thought you'd never goint to use?

[Brad Anderson]

On Sunday, 23 June 2013 at 01:34:53 UTC, Andrei Alexandrescu 
wrote:
> On 6/22/13 2:58 PM, monarch_dodra wrote:
>> long story short: we don't have rfind. C++ does.
>
> We do, just that it's for random-access ranges. C++ offers it 
> for bidirectional ranges too. We could of course support it if 
> bidirectional ranges were required to have something like 
> r1.before(r2) that, assuming r2 is reachable from r1, returns 
> the portion in r1 that's before r2.
>
> Andrei

How efficiently could before() be implemented?