#!/usr/bin/perl

use warnings;
use strict;

use Data::Dumper;

my $array_ref = [1, 2, 3, 4, 5];

my $array_of_hashes_ref = [
    {key => 4, name => 'label4'},
    {key => 2, name => 'label2'},
    {key => 5, name => 'label5'},
    {key => 1, name => 'label1'},
    {key => 3, name => 'label3'}
];

# WANT:
# $array_of_hashes_ref = [
#   {key => 1, name => 'label1'},
#   {key => 2, name => 'label2'},
#   {key => 3, name => 'label3'}
#   {key => 4, name => 'label4'},
#   {key => 5, name => 'label5'},
# ];

my $new_array_ref;

for my $key (@$array_ref)
{
    push @$new_array_ref, grep {$_->{'key'} == $key} @$array_of_hashes_ref;
}

warn Dumper($new_array_ref);