honeysql clone for PHP

honeysql.php

<?php

$data = 
  [':select' => [':a', ':b', ':c'],
   ':from' => [':foo']];
  
  
function recur(array $map) : object {
  return new \RecursiveIteratorIterator(
    new \RecursiveArrayIterator($map),
    \RecursiveIteratorIterator::CHILD_FIRST
  );
}
  
function map_to_sql(string $sql, array $map) : string {
    $out = [];
    $map = recur($map);
    foreach ($map as $key => $result) {
        switch (TRUE) {
            case $key === ':select':
                $out[] = 'SELECT ' . implode(', ', $result);
            break;
            case $key === ':from':
                $out[] = 'FROM ' . implode(' ', $result);
            break;
         }
    }

    return implode("\n", $out);
}



$out = map_to_sql('', $data);
var_dump($out);