For question 1: In general, WRT grep (which can only remove elements): yes, the relative order is maintained. For Far More Than You Ever Wanted to Know about this, see the recent Order in which grep/map receive elements.

For question 2: In general, WRT map (which is allowed to insert elements) the answer is no: 

>perl -wMstrict -le
"my @sorted = (1, 2, 3, 4, 5, 6);
 my @unsorted = map { $_, 99 } @sorted;
 print qq{@unsorted};
"
1 99 2 99 3 99 4 99 5 99 6 99

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In reply to Re: Will the sorting order of an array used in producing new arrays be retained? by AnomalousMonk
in thread Will the sorting order of an array used in producing new arrays be retained? by jospan

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