You didn't mention what you want marriage() to do, but it probably doesn't really matter. Here's an example of how you can do it without indices, using List::MoreUtils pairwise function.

It looks a lot like map, except that it takes two arrays, not one, and it aliases each pair of elements as $a and $b instead of $_. Its prototype requires that you pass it two arrays, whereas map is happy to receive a list not specifically held in an array.

Here's some example code where we've set up marriage() to just 'join' the elements together with a single space character binding them. You could easily modify it to return an arrayref, or even do away with it entirely and do all your work inside the pairwise{...} block.

use strict;
use warnings;

use List::MoreUtils qw/pairwise/;

my @rray1 = qw/ boy  boymonkey  boydog  /;
my @rray2 = qw/ girl girlmonkey girldog /;

our( $a, $b );

my @married 
    = pairwise{ marriage( $a, $b ) } @rray1, @rray2;

print "$_\n" for @married;


sub marriage {
    return join ' ', @_;
}
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The output will be:

boy girl
boymonkey girlmonkey
boydog girldog
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If you have warnings enabled, it's necessary to either say "our( $a, $b );", or no warnings qw/once/; (within the smallest scope possible scope, such as inside of the pairwise{...} block), or some other means of satisfying the "used only once" warning for $a and $b.

While pairwise{} is a convenience, I really don't see any big advantage over this:

my @married = map{ marriage( $rray1[$_], $rray2[$_] ) } 0 .. $#rray1;
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That snippet does iterate over the index which some nut may say is bad form, but on the other hand, it eliminates the need to pull in a CPAN module just for one line of sugar. The map{} approach even eliminates the need to worry about the "used only once" warning.