Online PHP editor | refs for e6to8

<?php function arity(callable $f): int { $ref = new ReflectionFunction($f); return $ref->getNumberOfParameters(); } var_dump(arity(fn() => null)); var_dump(arity(fn($a) => null)); var_dump(arity(fn($a, $b) => null)); var_dump(arity(fn($a, ...$args) => null)); var_dump(arity(fn(...$args) => null));