export type InputFactory<State, Inputs = undefined> = Inputs extends undefined
  ? (state$: Promise<State>) => Promise<State>
  : (inputs$: Promise<Inputs>, state$: Promise<State>) => Promise<State>

export function usePromise<State>(inputFactory: InputFactory<State>): State | null
export function usePromise<State>(inputFactory: InputFactory<State>, initialState: State): State
export function usePromise<State, Inputs>(
  inputFactory: InputFactory<State, Inputs>,
  initialState: State,
  inputs: Inputs,
): State

usePromise(
(inputs$, _) =>
    inputs$.then(([v]) => v), // why typescript want Promise<number[]> here???? I hovered my mouse to userPromise and I could see the generic params in usePromise was inferred to <0, [number]>. So I assumed the typechecker would like Promise<0> or Promise<number> instead of Promise<number[]> here
    0,
    [1000],
)