Module augmentation for @types/react that adds defintions of some of the new hooks in React 16.7.0-alpha.0

react-16.7.0-alpha.0.d.ts

import React from "react";
import {Context, RefObject} from "react";

declare module "react" {
    function useState<T>(initialState?: T): [T, (value: T) => void];
    function useEffect(effect: () => (() => void) | void, dependencies?: Array<any>): void;
    function useContext<C>(context: Context<C>): C;
    function useReducer<S>(reducer: (state: S, action: any) => S, initialState?: S, initialAction?: any): [S, (args: any) => void];
    function useCallback(callback: () => void, dependencies?: Array<any>): () => void;
    function useMemo<R>(fn: () => R, dependencies?: Array<any>): R;
    function useRef<T>(initialValue: T | null): RefObject<T>;
}

Just found this which is better: https://github.com/DefinitelyTyped/DefinitelyTyped/pull/30036/files#diff-48f3225134840da288f40a817697e2e9R564