import type { TransformFn } from '../../internal/function.js';
import { type Maybe } from '../core/maybe.js';
export type MaybeTryTransformFn<in T, out U> = TransformFn<T, Maybe<U>>;
/**
 *  Returns `null` or `undefined` if the _input_ is `null` or `undefined`,
 *  otherwise calls _transformer_ with the value and returns the result.
 *
 *  XXX:
 *  Some languages call this operation flatmap.
 *  But we don't provide `flatMap()` as alias of this function.
 *  because it's too hard to undarstand that "flatMap" operation for `T | null | undefined`.
 */
export declare function andThenForMaybe<T, U>(input: Maybe<T>, transformer: MaybeTryTransformFn<T, U>): Maybe<U>;