import { type DropInitialValueOperator } from '../types/index.mjs';
/**
 * Emits the previous and current values as a pair.
 * Does not emit until the source has emitted at least twice.
 *
 * @template A - The type of values from the source
 * @returns An operator that pairs consecutive values
 *
 * @example
 * ```ts
 * //  Timeline:
 * //
 * //  num$      1     2     3     4
 * //  pairs$          [1,2] [2,3] [3,4]
 * //
 * //  Explanation:
 * //  - pairwise emits the current and previous values as a tuple
 * //  - Nothing is emitted for the first value (no previous value yet)
 * //  - Useful for tracking changes between consecutive values
 *
 * const num$ = source<number>();
 *
 * const pairs$ = num$.pipe(pairwise());
 *
 * const valueHistory: (readonly [number, number])[] = [];
 *
 * pairs$.subscribe(([prev, curr]) => {
 *   valueHistory.push([prev, curr]);
 * });
 *
 * num$.next(1); // nothing logged
 *
 * assert.deepStrictEqual(valueHistory, []);
 *
 * num$.next(2); // logs: 1, 2
 *
 * assert.deepStrictEqual(valueHistory, [[1, 2]]);
 *
 * num$.next(3); // logs: 2, 3
 *
 * assert.deepStrictEqual(valueHistory, [
 *   [1, 2],
 *   [2, 3],
 * ]);
 *
 * num$.next(4); // logs: 3, 4
 *
 * assert.deepStrictEqual(valueHistory, [
 *   [1, 2],
 *   [2, 3],
 *   [3, 4],
 * ]);
 * ```
 */
export declare const pairwise: <A>() => DropInitialValueOperator<A, readonly [A, A]>;
//# sourceMappingURL=pairwise.d.mts.map