ts-data-forge/dist/array/impl/array-utils-element-access.d.mts

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/**
 * Safely retrieves an element at a given index from an array, returning an Optional.
 *
 * @example
 *
 * ```ts
 * const letters: readonly string[] = ['a', 'b', 'c'];
 *
 * const two = Arr.at(letters, 1);
 *
 * const last = Arr.at(-1)(letters);
 *
 * const missing = Arr.at(letters, 5);
 *
 * assert.deepStrictEqual(two, Optional.some('b'));
 *
 * assert.deepStrictEqual(last, Optional.some('c'));
 *
 * assert.deepStrictEqual(missing, Optional.none);
 * ```
 */
export declare function at<const Ar extends readonly unknown[]>(array: Ar, index: ArgArrayIndexWithNegative<Ar>): Optional<Ar[number]>;
export declare function at(index: SizeType.ArgArrWithNegative): <E>(array: readonly E[]) => Optional<E>;
/**
 * Returns the first element of an array as an Optional.
 *
 * @example
 *
 * ```ts
 * const users = [{ id: 1 }, { id: 2 }];
 *
 * const empty: { id: number }[] = [];
 *
 * const first = Arr.head(users);
 *
 * const none = Arr.head(empty);
 *
 * assert.deepStrictEqual(first, Optional.some({ id: 1 }));
 *
 * assert.deepStrictEqual(none, Optional.none);
 * ```
 */
export declare const head: <const Ar extends readonly unknown[]>(array: Ar) => Ar extends readonly [] ? None : Ar extends readonly [infer E, ...unknown[]] ? Some<E> : Ar extends NonEmptyArray<infer E> ? Some<E> : Optional<Ar[number]>;
/**
 * Returns the last element of an array as an Optional.
 *
 * @example
 *
 * ```ts
 * const queue = ['first', 'second'];
 *
 * const emptyQueue: string[] = [];
 *
 * const lastValue = Arr.last(queue);
 *
 * const none = Arr.last(emptyQueue);
 *
 * assert.deepStrictEqual(lastValue, Optional.some('second'));
 *
 * assert.deepStrictEqual(none, Optional.none);
 * ```
 */
export declare const last: <const Ar extends readonly unknown[]>(array: Ar) => Ar extends readonly [] ? None : Ar extends readonly [...unknown[], infer E] ? Some<E> : Ar extends NonEmptyArray<infer E> ? Some<E> : Optional<Ar[number]>;
/**
 * Alias for `head`.
 *
 * @see {@link head}
 */
export declare const first: <const Ar extends readonly unknown[]>(array: Ar) => Ar extends readonly [] ? None : Ar extends readonly [infer E, ...unknown[]] ? Some<E> : Ar extends NonEmptyArray<infer E> ? Some<E> : Optional<Ar[number]>;
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