11 lines
444 B
TypeScript
11 lines
444 B
TypeScript
export interface IPromise<T, V> {
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then<U, W>(callback: (x: T) => IPromise<U, W>): IPromise<U, W>;
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}
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export interface Promise<T, V> {
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then<U, W>(callback: (x: T) => Promise<T, U>): Promise<T, W>;
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}
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// error because T is string in the first declaration, and T is boolean in the second
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// Return type and callback return type are ok because T is any in this particular Promise
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var x: IPromise<string, number>;
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var x: Promise<any, string>; |