sort_by_order_monkey_patch.pl

#!/usr/bin/perl -l

use strict;
use warnings;

use Mojo::Util;
use Mojo::Collection;

Mojo::Util::monkey_patch('Mojo::Collection', sort_by_order => sub {
    my ($self, $order, $cb) = @_;

    local $_ = { map { $order->[$_] => $_ } 0..@{$order}-1 };

    return $self->sort( $cb );
});

print Mojo::Collection->new          ( { a => 2 }, { a => 1 }, { a =>3 } )
                      ->sort_by_order( [ 3, 2, 1 ], sub { $_->{$a->{a}} <=> $_->{$b->{a}} } )
                      ->map          ( sub { $_->{a} } )
                      ->join         ( ', ' );

# 3, 2, 1