import type { TransformFn } from '../../internal/function.js';
import type { Option } from './option.js';
/**
 *  Return the result of _transformer_ with using _input_ as an argument for it if _input_ is `Some(T)`.
 *  Otherwise, return _defaultValue_.
 *
 *  Basically, this operation is a combination `map()` and `unwrapOr()`.
 */
export declare function mapOrForOption<T, U>(input: Option<T>, defaultValue: U, transformer: TransformFn<T, U>): U;