import type { Args, GenericFn, GenericResolver } from "..";

/**
 * Create a tuple with one element.
 *
 * Sig: `<T>(x: T) => readonly [T]`
 *
 * @example
 * ```typescript
 * type R1 = Of1<1>;
 * //   ^?: readonly [1]
 * type R2 = Of1<"foo" | false>;
 * //   ^?: readonly ["foo" | false]
 * ```
 */
export type Of1<T> = readonly [T];

interface Resolver extends GenericResolver<[unknown], readonly [unknown]> {
  on1: ([x]: Args<this>) => [[], readonly [typeof x]];
}

/**
 * [Fn] Create a tuple with one element.
 *
 * Sig: `<T>(x: T) => readonly [T]`
 */
export default interface Of1Fn extends GenericFn<Resolver> {
  def: ([x]: Args<this>) => Of1<typeof x>;
}