11 lines
402 B
TypeScript
11 lines
402 B
TypeScript
interface Sequence<T> {
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each(iterator: (value: T) => void): void;
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map<U>(iterator: (value: T) => U): Sequence<U>;
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filter(iterator: (value: T) => boolean): Sequence<T>;
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groupBy<K>(keySelector: (value: T) => K): Sequence<{ key: K; items: T[]; }>;
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}
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var s: Sequence<string>;
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var s2 = s.groupBy(s => s.length);
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var s3 = s2.each(x => { x.key /* Type is K, should be number */ });
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