ducks.ts

import 'redux';

type Duck<T> = {
  reducer: (state: T) => T;
};
type GetBranch<T> = <R>(rootState: R) => T;
type DuckCreator<T> = (getBranch: GetBranch<T>) => Duck<T>;
interface DuckCreatorMap {
  [key: string]: DuckCreator<any>;
}

const combineDucks = <T extends DuckCreatorMap>(duckMap: T): DuckCreator<T> => {
  return {} as any;
};

interface Thing { id: string; name: string }
interface ThingState { things: Record<string, Thing> }
const getThingById = (thingId: string) => (state: ThingState) => state.things[thingId];
const thing = (prefix: string) => (getBranch: GetBranch<ThingState>) => {
  const reducer = (state: ThingState) => state;
  const loadThing = (thingId: string) => async (dispatch, getState) => {

  };
  return { reducer, loadThing };
};
const identity = <T>(t: T) => t;

const root = combineDucks({
  thing1: thing('THING_1'),
  thing2: thing('THING_2'),
  nested: combineDucks({
    thing3: thing('THING_3'),
  }),
  contexts: context('CTX', {
    thing4: thing('THING_4'),
  }),
})(identity);

// root.nested.thing.
// root.contexts.get('lkj').loadThing('')

// root.thing1.
// root.thing1