gale/type-experiments-04.ts

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TypeScript
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2024-08-02 14:45:14 -04:00
type OriginalType = {
key1: { sub1: string; sub2: string };
key2: { subA: string; subB: string };
};
type ValidKeys = keyof OriginalType;
type ValidSubKeys<K extends ValidKeys> = keyof OriginalType[K];
type FixedLengthArray<T, L extends number> = T[] & { length: L };
type EnforcedRecord<L extends number> = {
[K in ValidKeys]: FixedLengthArray<ValidSubKeys<K>, L>;
};
type FixedArr<Arr, Length extends number> = Arr & { length: Length };
function Func<L extends number>(arr1:FixedArr<string[], L>)
{
return arr1.length;
}
const test = Func<3>(["a", "b", "c"])
// Example usage:
const example: EnforcedRecord<2> = {
key1: ['sub1', 'sub2', 'sub1'], // Valid
key2: ['subA', 'subB'], // Valid
// key1: ['sub1'], // Invalid, TypeScript will give an error
// key2: ['subA', 'subB', 'subC'], // Invalid, TypeScript will give an error
};