Definition of Functional Programming
Functional Programming (FP) is a declarative programming paradigm that treats computation as the evaluation of mathematical functions. It emphasizes immutability, pure functions, and function composition, making programs more predictable and easier to reason about.
Characteristics of Functional Programming
1. Pure Functions
- Deterministic output for the same input
- No side effects
- Easier to test and debug
2. Immutability
- Data cannot be changed after creation
- Prevents unexpected state mutations
- Supports concurrent and parallel processing
3. First-Class and Higher-Order Functions
- Functions can be assigned to variables
- Functions can be passed as arguments
- Functions can be returned from other functions
4. Declarative Style
- Focuses on WHAT to do, not HOW to do it
- Reduces complexity of code
- Improves code readability
Key Concepts
- Function Composition
- Recursion
- Lazy Evaluation
- Pattern Matching
- Referential Transparency
Practical Applications
- Functional languages: Haskell, Erlang, Scala
- Functional programming in multi-paradigm languages
- JavaScript (map, reduce, filter)
- Python (functional programming modules)
- Scala (functional features)
Advantages
- Predictable code behavior
- Easier parallel processing
- Reduced side effects
- Improved code modularity
- Better testability
Challenges
- Learning curve for developers
- Performance overhead in some implementations
- Less intuitive for some problem domains
Related Paradigms
- object-oriented-programming
- procedural-programming
- Declarative Programming