kubk

// RxJS - FRP
const increment = new Subject<void>();
const decrement = new Subject<void>();
const add = new Subject<number>();

type State = number;

const count$ = merge(
  increment.pipe(mapTo((state: State) => state + 1))
  decrement.pipe(mapTo((state: State) => state - 1)),

kubk

interface Observer<T> {
    next(value: T)
    complete()
    error(error: unknown)
}

class Observable<T> {
    constructor(public subscribe: (observer: Observer<T>) => void) {}

    map(mapper: (x: T) => T): Observable<T> {