Merge pull request #176 from OliverJAsh/oja/fix/state-type-inference

Fix `useObservable` state generic inference

Author: zry656565

src/use-observable.ts

@@ -4,20 +4,13 @@ import useConstant from 'use-constant'
 
 import { RestrictArray } from './type'
 
-export type InputFactory<State, Inputs = undefined> = Inputs extends undefined
- ? (state$: Observable<State>) => Observable<State>
- : (inputs$: Observable<RestrictArray<Inputs>>, state$: Observable<State>) => Observable<State>
-
-export function useObservable<State>(inputFactory: InputFactory<State>): State | null
-export function useObservable<State>(inputFactory: InputFactory<State>, initialState: State): State
-export function useObservable<State, Inputs>(
- inputFactory: InputFactory<State, Inputs>,
- initialState: State,
- inputs: RestrictArray<Inputs>,
-): State
-
+export type InputFactory<State> = (state$: Observable<State>) => Observable<State>;
+export type InputFactoryWithInputs<State, Inputs> = (inputs$: Observable<RestrictArray<Inputs>>, state$: Observable<State>) => Observable<State>;
+export function useObservable<State>(inputFactory: InputFactory<State>): State | null;
+export function useObservable<State>(inputFactory: InputFactory<State>, initialState: State): State;
+export function useObservable<State, Inputs>(inputFactory: InputFactoryWithInputs<State, Inputs>, initialState: State, inputs: RestrictArray<Inputs>): State;
 export function useObservable<State, Inputs extends ReadonlyArray<any>>(
- inputFactory: InputFactory<State, Inputs>,
+ inputFactory: InputFactoryWithInputs<State, Inputs>,
  initialState?: State,
  inputs?: RestrictArray<Inputs>,
 ): State | null {
@@ -38,7 +31,7 @@ export function useObservable<State, Inputs extends ReadonlyArray<any>>(
  state$: Observable<State | undefined>,
  ) => Observable<State>)(inputs$, state$) as BehaviorSubject<State>
  } else {
- output$ = (inputFactory as (state$: Observable<State | undefined>) => Observable<State>)(
+ output$ = (inputFactory as unknown as (state$: Observable<State | undefined>) => Observable<State>)(
  state$,
  ) as BehaviorSubject<State>
  }