redux-no-bs

example.js

// in actionTypes.js
export const ADD = 'ADD'

// in actions.js
export const add = createAction(ADD)
export const addSquare = createAction(ADD, (x) => x * x)

// in reducers.js
export default createReducer(0, {
    [ADD]: (state, payload) => state + payload,
})

// example
test(t => {
    let state
    state = reducer(1, add(42))
    t.is(state, 43)

    state = reducer(1, addSquare(3))
    t.is(state, 10)
})

redux-utils.js

export function createAction(type, payloadCreator=identity) {
    return function actionCreator(...args) {
        return {
            type,
            payload: payloadCreator(...args)
        }
    }
}

export function createReducer(initialState, handlers) {
    return function reducer(state=initialState, { type, payload }) {
        const handler = handlers[type]
        return (handler)
            ? handler(state, payload)
            : state
    }
}

function identity (x) {
    return x
}