arrayImplodeIntoString

<?php

$picker = function ($item) {
    return $item;
};
function arrayImplodeIntoString(array $list, $picker, string $separator = ',') :string
{
    $first_element = $list[0]??null;
    if ($first_element) {
        $remaining_list = array_slice($list, 1);
        return array_reduce($remaining_list, function ($carry, $item) {
            return $carry . ','. $item;
        }, $first_element);
    }
    return null;
}


$list = [1, 2, 3];

echo arrayImplodeIntoString($list, $picker);