PHP 函数返回值的类型可以是怎么确定的？

functiongreet(string $name): string {

    return"Hello, $name!";

}

$name= "John Doe";

$greeting= greet($name);

functioncalcSum(int ...$numbers): float {

    returnarray_sum($numbers);

}

$result= calcSum(1, 2, 3);

functioncheckType($variable) {

    returngettype($variable);

}

$variable= 123;

$type= checkType($variable);

// psalm.xml 配置文件

<?xml version="1.0"?>

<psalm>

    <types>

        <method name="greet"class="App\Greetings">

            <return-type>string</return-type>

        </method>

    </types>

</psalm>

// 调用 Psalm

$psalm= newPsalm();

$psalm->analyzeFile('greetings.php');