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x/unknownutil/mod.ts>isTupleOf

🦕 A lightweight utility pack for handling unknown type
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function isTupleOf
import { isTupleOf } from "https://deno.land/x/unknownutil@v3.5.1/mod.ts";

Return a type predicate function that returns true if the type of x is TupleOf<T>.

import is from "./is.ts";

const predTup = [is.Number, is.String, is.Boolean] as const;
const a: unknown = [0, "a", true];
if (is.TupleOf(predTup)(a)) {
 // a is narrowed to [number, string, boolean]
 const _: readonly [number, string, boolean] = a;
}

Note that predTup must be readonly (as const) to infer the type of a correctly. TypeScript won't argues if predTup is not readonly because of its design limitation. https://github.com/microsoft/TypeScript/issues/34274#issuecomment-541691353

Type Parameters

T extends readonly Predicate<unknown>[]

Parameters

predTup: T