how to compose the existed Action / Reducer to make create multi instances on global redux store (combineReducer) in TypeScript

higher-order-lifter.ts

// how to compose the existed Action / Reducer to make create multi instances on global redux store (combineReducer) 
// inspired from https://github.com/reduxjs/redux/issues/897

/** liftAction lifting your existed Action */
export function liftAction<LType extends string, Arg, A>(
    /** lift key */
    liftedType: LType,
    /** original action generator */
    actionGenerator: (...args: Arg[]) => A
    /* considering react-thunk so i use `HIGHT_ORDER_ACTION` refers to `LType` */ 
): (...args: Arg[]) => { HIGHT_ORDER_ACTION: LType } & A {
    return function (...args) {
        const preAction = actionGenerator(...args)
        return {
            ...preAction, HIGHT_ORDER_ACTION: liftedType
        }
    }
}

/** liftReducer lifting your existed reducer */
export function liftReducer<LType extends string, A, State>(
    /** lift key */
    liftedType: LType,
    /** origin reducer, tips: state may be undefined */
    reducer: (state: State | undefined, action: A) => State
): (state: State | undefined, action: { HIGHT_ORDER_ACTION: LType } & A) => State {
    return function(state, action) {
        if (action.HIGHT_ORDER_ACTION === liftedType) {
            return reducer(state, action)
        } else {
            return state || reducer(state, action)
        }
    }
}