16 lines
445 B
JavaScript
16 lines
445 B
JavaScript
//// [promiseIdentityWithConstraints.ts]
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interface IPromise<T, V> {
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then<U extends T, W extends V>(callback: (x: T) => IPromise<U, W>): IPromise<U, W>;
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}
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interface Promise<T, V> {
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then<U extends T, W extends V>(callback: (x: T) => Promise<U, W>): Promise<U, W>;
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}
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// Error because constraint V doesn't match
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var x: IPromise<string, number>;
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var x: Promise<string, boolean>;
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//// [promiseIdentityWithConstraints.js]
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var x;
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var x;
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