import { S, T } from "./constants.js";
export type Either<L, R> = L | R;
export type Nullable<T> = Either<null, T>;
export type Lambda<I, O> = (value: I) => O;
export type Subscriber<T, Async extends boolean> = Lambda<T, Async extends true ? PromiseLike<void> : void>;
export type Subscribers<T, Async extends boolean> = Set<Subscriber<T, Async>>;
export type Transform<I, O> = Lambda<I, O>;
export type EventSync<I, O> = (transform?: Transform<I, O>) => {
    [S]: Nullable<Subscribers<O, false>>;
    [T]: Transform<I, O>;
};
export type EventAsync<I, O> = (transform?: Transform<I, PromiseLike<O>>) => {
    [S]: Nullable<Subscribers<O, true>>;
    [T]: Transform<I, PromiseLike<O>>;
};
export type EventAny<I = any, O = any> = Either<EventSync<I, O>, EventAsync<I, O>>;
export type InferSubscriber<T extends EventAny<any, any>> = T extends EventAsync<any, infer O> ? Subscriber<O, true> : T extends EventSync<any, infer O> ? Subscriber<O, false> : never;