A typechecked action type matcher for reducers

match.ts

type IndexableType = string | number

type Action<PossibleTypes extends IndexableType> = {
	type: PossibleTypes
	payload: any
}

type Matchers<
	PossibleTypes extends IndexableType,
	PossibleActions extends Action<PossibleTypes>,
	ReturnType> = {
		[SelectedType in PossibleTypes]: (payload: Payload<
			PossibleTypes,
			PossibleActions,
			SelectedType
		>) => ReturnType
	}

type Payload<
	PossibleTypes extends IndexableType,
	PossibleActions extends Action<PossibleTypes>,
	SelectedType extends PossibleTypes> = (PossibleActions & {
		type: SelectedType
	})['payload']

export const match = <
	PossibleTypes extends IndexableType,
	PossibleActions extends Action<PossibleTypes>,
	ReturnType>
	(
		action: PossibleActions,
		matchers: Matchers<PossibleTypes, PossibleActions, ReturnType>
	): ReturnType =>
	matchers[action.type](action.payload)