Some ways that Perl 6 is grand, part 2 of ?

Okay, this is really part 1b of ?, but…

In my earlier post, I used the zip operator to join two lists into a hash.

There was one obvious use of the operator that escaped me at the time, and that was how I sometimes need to create a new hash from the keys of two hashes, or keys and values. And now I think it's starting to look neat:

my %A = { a => 1, b => 2 };
my %B = { z => 9, y => 8 };

my %AB = %A.keys Z %B.keys;
# { "a" => "z", "b" => "y" }

%AB = %A.keys Z %B.values;
# { "a" => 9, "b" => 8 }

However, this is a bit unpredictable, since the hash key order is undefined. So if you expect sorted keys, do that at the same time:

%AB = %A.keys.sort Z %B.keys.sort;
# { "a" => y, "b" => z }

# Sort by B's values - two variants
%AB = %A.keys.sort Z map { %B{$_} }, %B.keys.sort;
%AB = %A.keys.sort Z %B.sort.map( { .value } );
# { "a" => 8, "b" => 9 }

The equivalent Perl 5.10 version would be:

use List::MoreUtils qw/zip/;
my @k = sort(keys(%A));
my @v = map { $B{$_} }, sort(keys(%B));
%AB = zip @k, @v;

I now have a nice-ish argument for upgrading to Perl 5.10.1 on $workplace's servers. :D

masak++ for helping a tired me with the map expression.
Chas. Owens++ for spotting the missing use statement for Perl 5.
Pm++ for another way of sorting by value, just what I was hoping for!
isec++ for spotting a missing sort() for Perl 5.