#!/usr/bin/env perl
use strict;
use warnings;
use Benchmark qw(:all);

my @array='aa' .. 'zz';

sub variation4 {
	my $idx = 0;
	my %hash; $hash{ $_ } = $idx++ for @array;
}

sub variation5 {
	my $idx = 0;
	my %hash;
	for (@array) {
		$hash{ $_ } = $idx++;
	}
}

cmpthese(-3, {
	'variation4' => \&variation4,
	'variation5' => \&variation5,
});

__END__
            Rate variation5 variation4
variation5 740/s         --        -4%
variation4 773/s         5%         --