How to iterate all k-subsets of a range in a specific order?

[Tommi]

On Friday, 5 October 2012 at 09:37:51 UTC, Ali Çehreli wrote:
>
> This brings up a question: Should all range types implement 
> opEquals() for "range equality" as opposed to "identity 
> equality" of the underlying range (i.e. Take.source in this 
> case).

But even if the range concept was altered so that all ranges have 
to implement opEquals(), it wouldn't be a very satisfying 
solution. That's because opEquals() could be a very slow function 
for some ranges, e.g. forward ranges, where you have to check 
each element's equality one by one. Using opEquals() like that 
could make traversing those subset iterations very slow.