use strict;
use warnings;

use Benchmark q{cmpthese};

my @arr = ( q{a} .. q{z} ) x 1_000;

cmpthese(
    -10,
    {
        useGrep => sub {
            my %seen;
            my @out = grep { !$seen{$_}++ } @arr;
            return @out;
        },
        useSlice => sub {
            my %seen;
            @seen{@arr} = ();
            my @out = keys %seen;
            return @out;
        },
        useRef => sub {
            my @out = keys %{ { map { $_ => undef } @arr } };
            return @out;
        },
    }
);