DIP67: Associative Ranges

[John Colvin via Digitalmars-d]

On Wednesday, 29 October 2014 at 17:36:41 UTC, H. S. Teoh via 
Digitalmars-d wrote:
> On Wed, Oct 29, 2014 at 05:23:07PM +0000, Brad Anderson via 
> Digitalmars-d wrote:
>> On Wednesday, 29 October 2014 at 06:59:09 UTC, bearophile 
>> wrote:
>> >This is very false. I have tons of cases where you only 
>> >iterate on
>> >values or keys. On the other hand I have suggested several 
>> >times that
>> >I'd like a byPairs (that yields keys-values tuple pairs).
>> >
>> 
>> It happens to me too but it's very much a minority of uses. 
>> Having
>> sets as well as maps would help replace some of these cases. 
>> Not all,
>> of course.
>> 
>> >
>> >>Doing byKey requires you to do a lookup to get the 
>> >>corresponding
>> >>value which just takes up cycles unnecessarily.
>> >
>> >Usually people use a "AA.byKey.zip(AA.byValue)" that is not 
>> >reliable.
>> 
>> Better than doing key lookups on every iteration but awfully 
>> ugly and
>> should be unnecessary. byPairs sounds good.
>
> I've submitted a PR for byPair before, but it was roadblocked 
> by the
> fact that people demand that it return std.typecons.Tuple, yet 
> we're not
> allowed to import Phobos in druntime. Other than this IMO 
> nitpicky
> issue, the code was already all ready to go many moons ago.
>
>
> T

Can byPair be implemented in phobos, or does it need to access 
private/package stuff in druntime?