import { isTupleOf } from "https://deno.land/x/unknownutil@v3.1.0/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 _: [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