#!/usr/bin/perl

use Tie::RecursiveCI;
tie %hash, 'Tie::RecursiveCI';

$hash{foo} = 10;
$hash{Foo} = 20;
$hash{bar}{blat} = 30;
$hash{BAR}{blAT} = 40;

for (sort keys %hash) {
  print "$_ => $hash{$_}\n";
}

for (sort keys %{ $hash{bAr} }) {
  print "$_ => $hash{bar}{$_}\n";
}