mcaruso

    $result = $arr
        ->column('values')
        ->merge()
        ->reduce(fn($carry, $item) => $carry + $item, 0)
        ->repeat('x');

    const head = ([x, ...xs]) => x;
    const tail = ([x, ...xs]) => xs;
    
    const map = (list, fn) => {
      if (list.length === 0) {
        return [];
      } else {
        return [fn(head(list)), ...map(tail(list), fn)];
      }
    };
    
    map([1, 2, 3], x => x + 1); // [2, 3, 4]