There's an typo in the code; the code block in the reduce statement should be

{ \($$a->{$b}) }
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Also, when I tried the code as given (after fixing the above typo), I got the error:

% perl rec_walk.pl
Can't call method "List::Util::reduce" on unblessed reference at rec_w
+alk.pl line 9.
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Here's the full code of the script that caused that error:

use strict;
my %myhash;
$myhash{bedrock}{flintstone}{fred} = 3;

my $ref = pointer_to_element(\%myhash, qw(bedrock flintstone fred));

sub pointer_to_element {
  require List::Util;
  return List::Util::reduce { \($$a->{$b}) } \shift, @_;
}
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I couldn't figure out why the error, so I switched the code to

use List::Util 'reduce';
sub pointer_to_element {
  return reduce { \($$a->{$b}) } \shift, @_;
}
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and it worked great. Tres cool.