export type List<T> = [T, any] | 0;

export type Talkback = 0 | 1;

export type Signal<A> =
  | ({ tag: 0 } & [(talkback: Talkback) => void])
  | ({ tag: 1 } & [A])
  | 0;

export interface Sink<A> { (signal: Signal<A>): void; }
export interface Source<A> { (sink: Sink<A>): void; }
export interface Operator<A, B> { (source: Source<A>): Source<B>; }

export type Subscription = [() => void];

export type Observer<A> = [(value: A) => void, () => void];

export type Subject<A> = [Source<A>, (value: A) => void, () => void];