import { ReadonlySignal } from './index';
/**
 * Create a signal that emits whenever the passed signal emits. The original
 * emitted value gets transformed by the passed function and the result gets
 * emitted.
 *
 * Example:
 * ```ts
 * const signal$ = makeSignal<number>();
 * const derived$ = deriveSignal(signal$, (n) => n + 100);
 * derived$.subscribe((v) => console.log(v));
 * signal$.emit(3); // will trigger console.log, echoing 103
 * ```
 * @param signal$ a signal.
 * @param transform a transformation function.
 * @returns a new signal that will emit the transformed data.
 */
export declare function deriveSignal<T, U>(signal$: ReadonlySignal<T>, transform: (data: T) => U): ReadonlySignal<U>;
/**
 * Coalesce multiple signals into one that will emit the latest value emitted
 * by any of the source signals.
 *
 * Example:
 * ```ts
 * const lastUpdate1$ = makeSignal<number>();
 * const lastUpdate2$ = makeSignal<number>();
 * const latestUpdate$ = coalesceSignals([lastUpdate1$, lastUpdate2$]);
 * latestUpdate$.subscribe((v) => console.log(v));
 * lastUpdate1$.emit(1577923200000); // will log 1577923200000
 * lastUpdate2$.emit(1653230659450); // will log 1653230659450
 * ```
 * @param signals$ an array of signals to observe.
 * @returns a new signal that emits whenever one of the source signals emits.
 */
export declare function coalesceSignals<T extends unknown[]>(signals$: {
    [P in keyof T]: ReadonlySignal<T[P]>;
}): ReadonlySignal<T[number]>;