When nesting map{}s inside each other, the inner map{} can not have any idea of what the outer map{}'s value of $_ is, without using a temporary variable, which is terribly inelegant. So I wrote this, which I intend to offer as a sacrifice on the altar of CPAN. Any comments are welcome.
package NestedMap;

require Exporter;
@ISA = qw(Exporter);
@EXPORT = qw(nestedmap);

use strict;
use warnings;

# [POD snipped out]

sub nestedmap(&@) {
    my $f = shift;
    map {
        local @NestedMap::stack = ($_, @NestedMap::stack);
        $f->($_);
    } @_
}

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You might use it thus (from the perldoc): 
# show all combinations of (A,B,C) (a,b,c) and (1,2,3)
print join("\n",
  nestedmap {
    nestedmap {
      nestedmap {
        join('',@NestedMap::stack[0..2])
      } qw(A B C)
    } qw(a b c)
  } qw(1 2 3)
);

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update: thanks to broquaint for pointing out that the example only works in 5.8.0. To get it to co-operate with 5.6.1, change 
nestedmap { ... } list

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to 
nestedmap sub { ... }, list

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In reply to Nested map by DrHyde

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