ts-data-forge/dist/functional/optional/impl/optional-flat-map.d.mts

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import { type Unwrap } from './types.mjs';
/**
 * Applies a function that returns an `Optional` to the value in an
 * `Some`. If the input is `None`, returns `None`.
 * This is the monadic bind operation for `Optional`.
 *
 * @example
 *
 * ```ts
 * const parseNumber = (input: string): Optional<number> => {
 *   const num = Number.parseInt(input, 10);
 *
 *   return Number.isNaN(num) ? Optional.none : Optional.some(num);
 * };
 *
 * const parsed = Optional.flatMap(Optional.some('10'), parseNumber);
 *
 * assert.deepStrictEqual(parsed, Optional.some(10));
 *
 * const flatMapParse = Optional.flatMap(parseNumber);
 *
 * assert.deepStrictEqual(flatMapParse(Optional.some('5')), Optional.some(5));
 *
 * assert.deepStrictEqual(flatMapParse(Optional.some('invalid')), Optional.none);
 * ```
 *
 * @template O The input `UnknownOptional` type.
 * @template S2 The value type of the `Optional` returned by the function.
 * @param optional The `Optional` to flat map.
 * @param flatMapFn The function to apply that returns an `Optional`.
 * @returns The result of applying the function, or `None`.
 */
export declare function flatMap<O extends UnknownOptional, S2>(optional: O, flatMapFn: (value: Unwrap<O>) => Optional<S2>): Optional<S2>;
export declare function flatMap<S, S2>(flatMapFn: (value: S) => Optional<S2>): (optional: Optional<S>) => Optional<S2>;
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