interface PromiseClass<A, P extends PromiseLike<A>> {
    new(callback: (resolve: (value?: A | P) => void, reject: (reason?: any) => void) => void): P;
}

const bar: PromiseClass<number, Bluebird<number>> = Bluebird; // OK

interface Options<A, P extends PromiseLike<A>, C extends PromiseClass<A, P>> {
    promise?: C;
}

function foo<A, P extends PromiseLike<A>, C extends PromiseClass<A, P>>(options: Options<A, P, C>) { /* empty */ }

foo({ promise: Bluebird.resolve(3) });

foo<number, Bluebird<number>, PromiseClass<number, Bluebird<number>>>({ promise: Bluebird.resolve(3) });

foo<number, Bluebird<number>, PromiseClass<number, Bluebird<number>>>({ promise: Bluebird.resolve(3) });

declare class PromisePool<
    A,                        // the type of value returned by the source
    P extends PromiseLike<A>, // the type of Promise returned by the source
    P2 extends PromiseLike<A>, // the type of Promise specified in `options`
    C extends PromisePool.PromiseClass<A, P2> // a helper class
    > {
    constructor(
        source: IterableIterator<P> | P | (() => (P | undefined)) | A,
        concurrency: number,
        options?: PromisePool.Options<A, P2, C>
    );

    promise(): P2;
    start(): P2;
}

declare namespace PromisePool {
    interface PromiseClass<A, P extends PromiseLike<A>> {
        new(callback: (resolve: (value?: A | P) => void, reject: (reason?: any) => void) => void): P;
    }

    interface Options<A, P extends PromiseLike<A>, C extends PromiseClass<A, P>> {
        promise?: C;
    }
}

declare class PromisePool<
    A,                        // the type of value returned by the source
    P extends PromiseLike<A>, // the type of Promise returned by the source
    P2 extends PromiseLike<A>, // the type of Promise specified in `options`
    C extends PromisePool.PromiseClass<A, P2> // a helper class
    > {
    constructor(
        source: IterableIterator<P> | P | (() => (P | undefined)) | A,
        concurrency: number,
        options?: PromisePool.Options<A, P2, C>
    );

    promise(): P2;
    start(): P2;
}

declare namespace PromisePool {
    interface PromiseClass<A, P extends PromiseLike<A>> {
        new(callback: (resolve: (value?: A | P) => void, reject: (reason?: any) => void) => void): P;
    }

    interface Options<A, P extends PromiseLike<A>, C extends PromiseClass<A, P>> {
        promise?: C;
    }
}