#! perl -slw
use strict;
use Benchmark qw[ cmpthese ];
use List::Util qw[ shuffle ];
use Data::Dump qw[ pp ];

sub buk1 { $a = $_ + rand @_ - $_ , $b = $_[$_], $_[$_] = $_[$a], $_[$a] = $b for 0 .. $#_; return @_; }
sub buk2 {
    die 'Need array reference' unless ref( $_[0] ) eq 'ARRAY';
    our( @aliased, $a, $b ); local( *aliased, $a, $b ) = $_[0];

    $a = $_ + rand @aliased - $_,
    $b = $aliased[ $_ ],
    $aliased[ $_ ] = $aliased[ $a ],
    $aliased[ $a ] = $b
        for 0 .. $#aliased;
    return;
}

sub tybalt {
    map $_->[0],
    sort { $a->[1] <=> $b->[1] }
    map [ $_, rand ], @_;
}

our $SANITY //= 0;

if( $SANITY ){
    my %tests;
    my @test = 1 .. 4;

    buk2( \@test ),
    ++$tests{ buk2     }{ join ' ', @test            } for 1 .. 10000;
    ++$tests{ buk1     }{ join ' ', buk1( @test )    } for 1 .. 10000;
    ++$tests{ tybalt   }{ join ' ', tybalt( @test )  } for 1 .. 10000;
    ++$tests{ ListUtil }{ join ' ', shuffle( @test ) } for 1 .. 10000;

    pp \%tests;
}

our $SIZE //= 100;
our @array = 1 .. $SIZE;

cmpthese -1, {
    buk1    => q[ my @shuf = buk1( @array ); ],
    buk2    => q[ buk2( \@array ) ],
    tybalt  => q[ my @shuf = tybalt( @array ); ],
    ListUtil=> q[ my @shuf = shuffle( @array ); ],
}