Overview
What is Functional Programming?
Section titled “What is Functional Programming?”Functional programming is a programming paradigm that treats computation as the evaluation of mathematical functions and avoids changing state and mutable data.
Core Principles
Section titled “Core Principles”Write declarative, composable code using functional programming principles that emphasize:
- Immutability - Data cannot be changed after creation
- Pure Functions - Functions always return the same output for the same input with no side effects
- First-Class Functions - Functions as values that can be assigned, passed, and returned
- Declarative Style - Focus on what to compute, not how to compute it
- Composability - Build complex functions from simple ones
Benefits
Section titled “Benefits”✅ Predictability - Pure functions are deterministic and easier to reason about ✅ Testability - Pure functions are easy to test in isolation ✅ Reusability - Small, focused functions can be composed and reused ✅ Parallelization - Immutable data is inherently thread-safe ✅ Maintainability - Less state and side effects reduce bugs ✅ Debugging - Easier to trace and debug without hidden state
Key Topics
Section titled “Key Topics”Core Concepts
Section titled “Core Concepts”- Pure Functions
- Immutability
- First-Class Functions
- Higher-Order Functions
Function Composition
Section titled “Function Composition”- Compose and Pipe
- Multi-Function Composition
- Point-Free Style
Currying and Partial Application
Section titled “Currying and Partial Application”- Function Transformation
- Specialized Functions
- Practical Applications
Functors and Monads
Section titled “Functors and Monads”- Maybe/Option Type
- Either/Result Type
- Error Handling
Functional Data Structures
Section titled “Functional Data Structures”- Immutable Lists
- Persistent Data Structures
- Efficient Updates
Recursion
Section titled “Recursion”- Tail-Call Optimization
- Trampolines
- Recursive Patterns
Lazy Evaluation
Section titled “Lazy Evaluation”- Generators
- Infinite Sequences
- Performance Optimization
Common Patterns
Section titled “Common Patterns”- Memoization
- Point-Free Style
- Pipeline Operations
Error Handling
Section titled “Error Handling”- Railway-Oriented Programming
- Result Types
- Safe Composition
Getting Started
Section titled “Getting Started”Start with understanding pure functions and immutability, then progress to function composition and higher-order functions. Once comfortable with the basics, explore functors, monads, and advanced patterns.
Recommended Libraries
Section titled “Recommended Libraries”- Ramda - Practical functional library for JavaScript
- fp-ts - Functional programming in TypeScript
- Lodash/fp - Functional variant of Lodash
- Immer - Immutable state updates with JavaScript
- Immutable.js - Persistent immutable data structures