use strict;
use warnings;
use List::MoreUtils;
use Benchmark qw(cmpthese);

my @values = map {int rand 10} 1 .. 1000;

for my $sub (\&UtilsM, \&UtilsH, \&Grep, \&Map, \&For,) {
    print join ("\t", sort $sub->(@values)), "\n";
}

cmpthese (-1, {
        UtilsM => sub {UtilsM (@values)},
        UtilsH => sub {UtilsH (@values)},
        Grep  => sub {Grep (@values)},
        Map   => sub {Map (@values)},
        For   => sub {For (@values)},
    }
);


sub UtilsM {
    return List::MoreUtils::uniq (@_);
}

sub UtilsH {
    my %h;
    return map { $h{$_}++ == 0 ? $_ : () } @_;
}

sub Grep {
    my %unique =();

    grep {$unique{$_} = undef} @_;
    return keys %unique;
}

sub Map {
    my %unique =();

    map {$unique{$_} = undef} @_;
    return keys %unique;
}

sub For {
    my %unique =();

    $unique{$_} = undef for @_;
    return keys %unique;
}

##</code><code>##

          Rate   Grep    For UtilsH    Map UtilsM
Grep    5068/s     --    -0%    -6%   -22%   -63%
For     5068/s     0%     --    -6%   -22%   -63%
UtilsH  5410/s     7%     7%     --   -17%   -61%
Map     6502/s    28%    28%    20%     --   -53%
UtilsM 13863/s   174%   174%   156%   113%     --