use strict;
use warnings;
use Benchmark qw(cmpthese);

my @list = (0..100);

cmpthese (-3, {
  c_style => sub { 
    for (my $i = 0; $i <= $#list; $i += 2) {
      $list[$i] = 'hi';
    }
  },
  slice     => sub { $_ = 'hi' for @list[map {$_ * 2} 0..$#list/2] },
  modulo    => sub { $_ % 2 or $list[$_] = 'hi' for 0..$#list; },
  doubler   => sub { $list[$_ * 2] = 'hi' for 0..@list/2; },
  evilgrep  => sub { @list[grep{!$_&1}0..$#list]= ('hi')x@list; }
});

### RESULTS ###

evilgrep  8006/s       --      -5%     -17%     -39%     -41%
modulo    8453/s       6%       --     -12%     -35%     -37%
slice     9630/s      20%      14%       --     -26%     -29%
c_style  13041/s      63%      54%      35%       --      -3%
doubler  13509/s      69%      60%      40%       4%       --