Thinking Functionally in PHP

Preface

Introduction

1. Functional vs. Procedural
2. Object-Oriented Code
3. Functional Style? Functional Language?
4. Type Systems
5. What to Expect
6. Part One

Pure Functions

1. Define “Pure”
2. Composing Functions
3. Binary Functions

First Class Functions

1. Anonymous Functions
2. Closure Objects
3. Short Lambdas
4. Object Binding

Memoization

Currying

Mapping

Filter

Reducing

Concatenation

Recursion

1. Recursion

Immutable Value Objects

1. What PHP Does
2. Making It Immutable
3. Objects, Functionally
4. Evolvable Objects
5. Dependencies
6. Entity Objects
7. Intra-Function Immutability
8. Part Two

Category Theory

1. What Is a Category?
2. Objects
3. Some Definitions
4. Structure
5. Let’s Get Meta
6. Isomorphism
7. Monoids

Categories in Code

1. Converting Structure
2. Function Objects

Fun With Functors

1. Combining Functors
2. Monads in Programming
3. Anatomy of a PHP Monad

Algebraic Data Types

1. Products
2. Product Types in PHP
3. Coproducts
4. Coproducts in PHP
5. Part Three

Handling Null

1. The Problem
2. The Example
3. The Category Theory Solution
4. The Programming Solution
5. An Alternate Implementation
6. A Note on Types

Either/Or and Error Handling

1. The Problem
2. The Example
3. The Category Theory Solution
4. The Programming Solution
5. Either Either?

Tracking Data

1. The Problem
2. The Example
3. The Category Theory Solution
4. The Programming Solution

Combining Monadic Behavior

1. The Example
2. The General Approach
3. Binding
4. The Lexers
5. Testing
6. Analysis
7. Being Lazy
8. Part Four

Features of Functional Languages

1. Auto-Currying
2. Recursion Optimization
3. Isomorphic Optimization
4. Function Composition
5. Function Naming
6. Generics
7. Callable Types
8. Comprehensions
9. Integrated Optionals
10. Optional Chaining
11. A Native Bind Operator
12. Enumerated Types

When to Go Functional

1. Avoid Global State
2. Make Pure Functions
3. Isolate IO
4. List Application
5. Embrace Value Objects
6. Embrace Functions as Values
7. Make Single-Method Callable Services
8. Think in Terms of Pipelines and Data Flow
9. Use Maybe and Either for Error Handling
10. Don’t Overdo It

Further Resources

1. Books
2. Videos
3. Papers