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

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import { type Unwrap } from './types.mjs';
/**
 * Maps an {@link Optional}<S> to {@link Optional}<S2> by applying a function to
 * a contained value. If the {@link Optional} is {@link None}, it
 * returns {@link Optional.none}. Otherwise, it applies the `mapFn` to the
 * value in `Some` and returns a new `Some` with the result.
 *
 * @example
 *
 * ```ts
 * const numberOptional = Optional.some(21);
 *
 * const mapped = Optional.map(numberOptional, (value) => value * 2);
 *
 * assert.deepStrictEqual(mapped, Optional.some(42));
 *
 * const mapToLength = Optional.map((text: string) => text.length);
 *
 * assert.deepStrictEqual(mapToLength(Optional.some('abc')), Optional.some(3));
 *
 * assert.deepStrictEqual(mapToLength(Optional.none), Optional.none);
 * ```
 *
 * @template O The input `UnknownOptional` type.
 * @template S2 The type of the value returned by the mapping function.
 * @param optional The `Optional` to map.
 * @param mapFn The function to apply to the value if it exists.
 * @returns A new `Optional<S2>` resulting from the mapping, or
 *   `None` if the input was `None`.
 */
export declare function map<O extends UnknownOptional, S2>(optional: O, mapFn: (value: Unwrap<O>) => S2): Optional<S2>;
export declare function map<S, S2>(mapFn: (value: S) => S2): (optional: Optional<S>) => Optional<S2>;
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