Sorting according to a primary and secondary criterion

[Joseph Rushton Wakeling]

On 07/17/2013 02:07 PM, bearophile wrote:
> Another way is to use something like this, but this needs some memory:
> 
> idx.schwartzSort!(i => tuple(arr1[i], arr2[i]));

Actually, I don't find it needs any more memory than regular schwartzSort (which
I was using anyway), but it does cost _speed_ -- quite a lot. :-(