Typescript重载箭头函数不起作用

function myFunc(param: string): string;
function myFunc(param: number): number;
function myFunc(param: string | number): string | number {
    if (typeof param === 'string') {
        return `Hello, ${param}`;
    } else {
        return param * 2;
    }
}

const myFunc = (param: string | number): string | number => {
    if (typeof param === 'string') {
        return `Hello, ${param}`; // 这里 TypeScript 知道 param 是 string 类型
    } else {
        return param * 2; // 这里 TypeScript 知道 param 是 number 类型
    }
};

const createMyFunc = () => {
    return (param: string | number): string | number => {
        if (typeof param === 'string') {
            return `Hello, ${param}`;
        } else {
            return param * 2;
        }
    };
};

const myFunc = createMyFunc();

function greet(name: string): string;
function greet(names: string[]): string[];
function greet(nameOrNames: string | string[]): string | string[] {
    if (Array.isArray(nameOrNames)) {
        return nameOrNames.map(name => `Hello, ${name}`);
    } else {
        return `Hello, ${nameOrNames}`;
    }
}

console.log(greet('Alice')); // 输出: Hello, Alice
console.log(greet(['Alice', 'Bob'])); // 输出: [ 'Hello, Alice', 'Hello, Bob' ]