## 🔹 Practical Example: Redux-like Store

function createStore(reducer, initialState) {
  let state = initialState;
  const listeners = [];

  const getState = () => state;

  const dispatch = (action) => {
    state = reducer(state, action);
    listeners.forEach(listener => listener());
  };

  const subscribe = (listener) => {
    listeners.push(listener);
    return () => {
      const index = listeners.indexOf(listener);
      listeners.splice(index, 1);
    };
  };

  return { getState, dispatch, subscribe };
}

// Reducer (pure function)
function counterReducer(state = 0, action) {
  switch(action.type) {
    case 'INCREMENT': return state + 1;
    case 'DECREMENT': return state - 1;
    default: return state;
  }
}

// Usage
const store = createStore(counterReducer);
store.subscribe(() => console.log(store.getState()));
store.dispatch({ type: 'INCREMENT' }); // Logs: 1

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## 🔹 Best Practices
1. Strive for purity when possible
2. Limit side effects to controlled areas
3. Use immutable data with libraries like Immer
4. Compose small functions into larger ones
5. Document function signatures clearly

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### 📌 What's Next?
In Part 9, we'll cover:
➡️ Error Handling Strategies
➡️ Debugging Techniques
➡️ Performance Optimization
➡️ Memory Management

#JavaScript #FunctionalProgramming #CleanCode 🚀

Practice Exercise:
1. Convert an imperative function to pure FP style
2. Implement a pipe() function (left-to-right composition)
3. Create a memoization higher-order function