Higher order collection methods

Collections have higher order methods, this are methods that can be chained , like groupBy() , map() ... Giving you a fluid syntax. This example calculates the price per group of products on an offer.

 1$offer = [
 2        'name'  => 'offer1',
 3        'lines' => [
 4            ['group' => 1, 'price' => 10],
 5            ['group' => 1, 'price' => 20],
 6            ['group' => 2, 'price' => 30],
 7            ['group' => 2, 'price' => 40],
 8            ['group' => 3, 'price' => 50],
 9            ['group' => 3, 'price' => 60]
10        ]
11];
12 
13$totalPerGroup = collect($offer['lines'])->groupBy('group')->map(fn($group) => $group->sum('price'));