Merged
Better type for reduce if not ininitial value is given#2205
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| test('reduce', () => { | ||
| // With an initial value, the result type is the accumulator type `R`. | ||
| (l: List<number>) => { |
| }; | ||
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| // With an initial value (overload 1), the reduction is typed `R`. | ||
| (l: List<number>) => { |
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| // Without an initial value and a reducer that returns a value (`R = V`), | ||
| // the result type `V` is inferred from the values — no annotation needed. | ||
| (l: List<number>) => { |
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| // Without an initial value but a reducer that returns a different type `R`, | ||
| // the reduction is typed `V | R`, since the first value (a `V`) seeds it. | ||
| (l: List<number>) => { |
| }; | ||
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| // Keyed collection: key is `K`. | ||
| (m: Map<string, number>) => { |
| }; | ||
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| // Set collection: value and key are both `T`. | ||
| (s: Set<number>) => { |
| }; | ||
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| // Base Collection. | ||
| (c: Collection<string, number>) => { |
| }); | ||
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| test('reduceRight', () => { | ||
| (l: List<number>) => { |
| ).type.toBe<string>(); | ||
| }; | ||
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| (l: List<number>) => { |
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[TypeScript]:
reduce/reduceRightwithout an initial value now infer the result type from the collection's values when the reducer returns a value (e.g.list.reduce((a, b) => a + b)infersnumber), matchingArray#reduce. Previously an explicit type argument was required.