如何实现在整数上参数化的Rust构造函数？

我想构造一个在整数上参数化的对象。尝试了以下操作：

struct Alpha<T> {
    num: T,
}

impl<T: Integer> Alpha<T> {
    fn new() -> Alpha<T> {
        Alpha { num: 0 }
    }
}

代码是。怎么了

怎么了

这是：

struct Foo;
impl Integer for Foo { … }
Alpha::<Foo>::new() // This should work as `Foo: Integer` and that's
                    // the only condition on `Alpha::new`.
                    // But it would need to create a instance
                    // of `Foo` from `0`.
                    // But the compiler has no idea how to do that!

---

谢谢我不遵循Foo的例子，但我认为它不像我在Haskell中习惯的那样简单。我试图更好地解释Foo的例子。

struct Foo;
impl Integer for Foo { … }
Alpha::<Foo>::new() // This should work as `Foo: Integer` and that's
                    // the only condition on `Alpha::new`.
                    // But it would need to create a instance
                    // of `Foo` from `0`.
                    // But the compiler has no idea how to do that!

impl<T: Integer> Alpha<T> {
    fn new() -> Alpha<T> {
        Alpha { num: Zero::zero() }
    }
}