Implementing Undo Function using Sagas

Provide an example of a saga that handles undo actions by reverting the state to its previous value using the stored history.

import { put, takeLatest } from 'redux-saga/effects';

// Action Types
const UNDO_ACTION = 'UNDO_ACTION';
const REVERT_STATE = 'REVERT_STATE';

// Saga to listen for the undo action and revert the state
function* handleUndoAction(action) {
    // Assuming we have the previous state stored
    const prevState = action.payload.prevState;
    yield put({ type: REVERT_STATE, payload: prevState });
}

// Watcher Saga
function* watchUndoAction() {
    yield takeLatest(UNDO_ACTION, handleUndoAction);
}

export default watchUndoAction;

This saga listens for an 'UNDO_ACTION', then triggers another action to revert the state of the application to its previous state. The previous state is assumed to be part of the action payload. 'takeLatest' ensures that if multiple UNDO_ACTIONs are dispatched in quick succession, only the latest will be considered.