rivo/List/IsList.d.ts

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import type { List } from ".";
import type { IsFixedLength } from "../Ary/IsFixedLength";
import type { Args, Fn } from "../HKT";
import type { AssertBool } from "../helpers";

/**
 * Check if a value is a {@link List} (i.e., fixed-length tuple).
 *
 * Sig: `(x: unknown) => boolean`
 *
 * @example
 * ```typescript
 * type R1 = IsList<readonly [1, 2, 3]>;
 * //   ^?: true
 * type R2 = IsList<[1, 2, 3, 4]>;
 * //   ^?: true
 * type R3 = IsList<readonly []>;
 * //   ^?: true
 * type R4 = IsList<string[]>;
 * //   ^?: false
 * type R5 = IsList<readonly [1, 2, 3, ...number[]]>;
 * //   ^?: false
 * ```
 */
export type IsList<T> = AssertBool<T extends List ? IsFixedLength<T> : false>;

/**
 * [Fn] Check if a value is a {@link List} (i.e., fixed-length tuple).
 *
 * Sig: `(x: unknown) => boolean`
 */
export default interface IsListFn extends Fn<[unknown], boolean> {
  def: ([x]: Args<this>) => IsList<typeof x>;
}