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

my @source = 1 .. 1000000;
my @result = @source;

cmpthese (-3,
    {
        for  => '@result = test_for ()',
        map  => '@result = test_map ()',
        mapf => '@result = test_mapf ()',
        forv => 'test_for ()',
        mapv => 'test_mapf ()',
    });


sub test_for {
    my @sqrt_results;
    for my $result (@source) {
        push @sqrt_results , sqrt($result);
    }

    return @sqrt_results;
}


sub test_map {
    return my @sqrt_results = map { sqrt $_ } @source;
}


sub test_mapf {
    return map { sqrt $_ } @source;
}