import type { AsyncTransformFn } from '../internal/function.js';
import { type Nullable, type NotNull } from './nullable.js';
/**
 *  Return the result of _transformer_ with using _input_ as an argument for it if _input_ is not `null`,
 *  Otherwise, return `null`.
 *
 *  * `U` must not be `Nullable<*>`.
 *      * If you'd like return `Nullable<*>` as `U`, use `andThen()`.
 *      * If the result of _transformer_ is `null`, this throw an `Error`.
 */
export declare function mapAsyncForNullable<T, U>(input: Nullable<T>, transformer: AsyncTransformFn<T, NotNull<U>>): Promise<Nullable<U>>;