React Redux: infer Redux props from mappers

foo.ts

import React, { SFC } from 'react';
import { MapDispatchToPropsParam, MapStateToPropsParam } from 'react-redux';
import { StateRoot } from 'reducers/types';
import { AnyAction, Dispatch } from 'redux';

//
// Helpers
//

const createSubType = <T extends any>() => <SubType extends T>(subType: SubType) => subType;

// Default dispatch props for react-redux
type DefaultDispatchProps = { dispatch: Dispatch };

// This helper function provides type inference to the `mapStateToProps` function params.
// We use the return type of this function to infer the `StateProps`.
const createMapStateToProps = <OwnProps extends {}>() =>
  createSubType<MapStateToPropsParam<any, OwnProps, StateRoot>>();

// This helper function provides type inference to the `mapDispatchToProps` function params.
// We use the return type of this function to infer the `DispatchProps`.
const createMapDispatchToProps = <OwnProps extends {}>() =>
  createSubType<MapDispatchToPropsParam<any, OwnProps>>();

type GetStateProps <
  MapStateToProps extends MapStateToPropsParam < any , any , any >
> = MapStateToProps extends MapStateToPropsParam<infer StateProps, any, any> ? StateProps : never;

type GetDispatchProps <
  MapDispatchToProps extends MapDispatchToPropsParam < any , any >
> = MapDispatchToProps extends MapDispatchToPropsParam<infer DispatchProps, any>
  ? DispatchProps
  : never;

type GetReduxProps <
  MapStateToProps extends MapStateToPropsParam < any , any , any > = null ,
  MapDispatchToProps extends MapDispatchToPropsParam < any , any > = DefaultDispatchProps
> = GetStateProps<MapStateToProps> & GetDispatchProps<MapDispatchToProps>;

//
// Begin example
//

type Photo = { title: string };

// Selector
declare const getPhotoById: (state: StateRoot, photoId: string) => Photo;
// Action creator
declare const likePhoto: (photoId: string) => AnyAction;

type OwnProps = {
  photoId: string;
};
// Infer the connected props from the mapping functions
type ReduxProps = GetReduxProps<typeof mapStateToProps, typeof mapDispatchToProps>;
type Props = OwnProps & ReduxProps;

export const LikePhotoButton: SFC<Props> = ({ photoId, photo, likePhoto }) => (
  <button
    onClick={() => {
      likePhoto(photoId);
    }}
  >
    {photo.title}
  </button>
);

const mapStateToProps = createMapStateToProps<OwnProps>()((state, ownProps) => ({
  photo: getPhotoById(state, ownProps.photoId),
}));

const mapDispatchToProps = createMapDispatchToProps<OwnProps>()({
  likePhoto,
});