import type { Merge } from "./Merge";
// @ts-ignore - Only used in doc comments
import type MergeFn from "./Merge";
import type { Args, Fn } from "../HKT";

/**
 * The flipped version of {@link Merge}.
 *
 * The `R` suffix (short for **R**ight or **R**everse) means that the arguments are flipped.
 *
 * Sig: `(r: object, l: object) => object`
 *
 * @example
 * ```typescript
 * type A = { a: number; b?: string };
 * type B = { a: boolean; c: string };
 * type R = MergeR<B, A>;
 * //   ^?: { a: boolean; b?: string; c: string }
 * ```
 */
export type MergeR<R extends object, L extends object> = Merge<L, R>;

/**
 * [Fn] The flipped version of {@link MergeFn}.
 *
 * Sig: `(r: object, l: object) => object`
 *
 * The `R` suffix (short for **R**ight or **R**everse) means that the arguments are flipped.
 */
export default interface MergeRFn extends Fn<[object, object], object> {
  def: ([r, l]: Args<this>) => MergeR<typeof r, typeof l>;
}