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Question

想为https://github.com/paldepind/union-type

撰写d.ts文件寻求帮助

使用下面的联合类型

let Maybe = Type({
    Nothing: []
    , Just: [Number]
})

如果Maybe.Nothing()输入错误为Maybe.None()

，我很乐意看到编译错误

我尝试从对象文字中捕获键，但编译器仍然无法识别结果类型Nothing中的Just和Maybe。

interface Obj {
    prototype: any
    case: (x: {[index: string]: (...args) => any}) => any
    caseOn: (x: {[index: string]: (...args) => any}) => any
}
interface Union<T> {
    (desc: T): T & Obj
}
var Type: Union<{[key: string]: any}>
export = Type

Answer 1

我认为您所寻找的是索引类型，请参阅本手册的Advanced Types部分，了解有关其工作原理的更多说明。我也一直在为paldepind / union-type制作一个声明文件，但它不完整：

    public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();

        List<Rec> data = new List<Rec>();
        var rnd = new Random();
        for (int i = 0; i < 3000; i++)
        {
            data.Add(new Rec() { Group = string.Format("Group{0}", rnd.Next(1,3)), Name = string.Format("Item{0}", rnd.Next(1,50)), Age = rnd.Next(10,100) });
        }

        var dataView = new ListCollectionView(data);
        dataView.GroupDescriptions.Add(new PropertyGroupDescription("Group"));

        dataGrid.ItemsSource = dataView;
    }
}

我也在尝试在TS中找到一个解决方法...

Answer 2

如果你正在寻找一个可能的实现，这是我曾经写过的一个

Resu homework(double d[],int l){
     Resu result;
..
.. your magic must be here
..
    return result;
}

那就是说，我觉得它很无用，只需要知道/** * A Maybe implementation * that is JavaScript first * i.e. simple typed abstraction over null/undefined */ export class Maybe<T>{ private _value: T; /** Based on value it will be Some or None */ constructor(value: T) { this._value = value; } /** Shorthand for constructor */ static Some<T>(value: T): Maybe<T> { if (value === null || value === undefined) { throw new Error('value for some cannot be null or undefied'); } return new Maybe(value); }; static None<T>(): Maybe<T> { return new Maybe(null); }; get value(): T { return this._value; } get isSome() { return this._value !== null && this._value !== undefined; } get isNone() { return !this.isSome; } map<U>(mapper: (now: T) => U): Maybe<U> { if (this.isSome) { return new Maybe(mapper(this._value)); } else { return new Maybe(null); } } }并在对象上使用null/undefined属性就更简单了（更多https://medium.com/@basarat/null-vs-undefined-in-typescript-land-dc0c7a5f240a）

union-type js的Typescript定义

2 个答案:

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