Functional Programming vs. Object-Oriented Programming (OOP)

Functional Programming (FP) and Object-Oriented Programming (OOP) are two of the most popular programming paradigms. Each has its strengths and trade-offs, depending on the problem you're solving. Let’s break it down!

1️⃣ Core Concepts

2️⃣ Key Differences

🔹 State & Mutability

• FP: Data is immutable; instead of modifying data, you create new copies.
• OOP: Objects can be modified internally, which can lead to unintended side effects.

🔹 Example:

• FP (Immutable):

  js
  CopyEdit
  const increment = (num) => num + 1; console.log(increment(5)); // 6 

• OOP (Mutable):

  js
  CopyEdit
  class Counter {   constructor() {     this.value = 0;   }   increment() {     this.value += 1;   } } const counter = new Counter(); counter.increment(); console.log(counter.value); // 1 

🔹 Code Reusability & Modularity

• FP: Uses higher-order functions and function composition for reuse.
• OOP: Uses inheritance and polymorphism to share behavior.

🔹 Example:

• FP (Higher-Order Function):

  js
  CopyEdit
  const multiply = (factor) => (num) => num * factor; const double = multiply(2); console.log(double(5)); // 10 

• OOP (Inheritance):

  js
  CopyEdit
  class Animal {   speak() {     console.log("Animal sound");   } } class Dog extends Animal {   speak() {     console.log("Bark!");   } } const dog = new Dog(); dog.speak(); // "Bark!" 

🔹 Concurrency & Performance

• FP: More efficient for parallel processing because functions don’t share state.
• OOP: More prone to race conditions and locking issues due to shared mutable state.

🔹 Example:

• FP works well in multi-threaded environments (e.g., JavaScript’s .map() function can run in parallel).

3️⃣ When to Use FP vs. OOP?

🚀 Final Thoughts

• FP is great for predictable, testable, and scalable applications, especially when dealing with large datasets or concurrency.
• OOP is ideal for applications that require complex state management and real-world entity modeling.
• Many modern languages support both paradigms (e.g., JavaScript, Python, Scala, Kotlin), so you don’t always have to choose just one.