Gain insights into functional programming in PHP. Learn about pure functions, immutable data, and monads. Explore error handling and apply principles through practical projects.

fp15aug.tar.gz

php7.4

ch8-phonebook

php8.1

purescript

python-pytoolz

chapter5-challenge1

AMQP

eris-testing-lesson

AMQP-Challenge

eris-testing-challenge

Functional programming is a paradigm that emphasizes expressing program logic as compositions of pure functions. PHP is a good fit for functional programming as functions are first-class citizens in its userland.
 
This course introduces you to the core concepts of functional programming, like pure functions, immutable data structures, and referential transparency. From there, you'll explore ways to handle errors with default values and callbacks while also exploring sum types such as Either or Maybe. Next, you'll look at functors before diving deep into monads, including IO, State, Reader, and List.
 
By the end of this course, you'll have a keen understanding of how to apply these principles in practice through a worked-out project. Not only will you know another way to program, but you’ll also feel confident enough to apply these ideas to your projects in PHP.

Learn Functional Programming in PHP

## What's immutability?

Anything considered **immutability** means that something does *not* change. To think that the state in an FP-driven application doesn’t change is overly simplistic and baseless. State does change, but it does so gracefully.
The idea of immutability extends beyond assigning a value to a variable just once. It requires a vigilant discipline, which comes from avoiding the recurring assignments, which is common in imperative style programming. Sadly, PHP has neither the kind of immutable data structures present in functional languages such as OCaml, nor the kind of variables that define languages like Haskell and Elm. The explicit expressions of immutability in PHP are constants and immutable data structures such as immutable lists, tries, and value objects.

## Constants in PHP

There exist two ways to define constants in PHP:
- The `const` keyword
- The `define` syntax

> **Note:** PHP PSR coding standards dictate that the names of constants should be in uppercase and separated by underscores.

# What's immutability?

Anything considered **immutability** means that something does *not* change. To think that the state in an FP-driven application doesn’t change is overly simplistic and baseless. State does change, but it does so gracefully.
The idea of immutability extends beyond assigning a value to a variable just once. It requires a vigilant discipline, which comes from avoiding the recurring assignments, which is common in imperative style programming. Sadly, PHP has neither the kind of immutable data structures present in functional languages such as OCaml, nor the kind of variables that define languages like Haskell and Elm. The explicit expressions of immutability in PHP are constants and immutable data structures such as immutable lists, tries, and value objects.

# Constants in PHP

There exist two ways to define constants in PHP:
- The `const` keyword
- The `define` syntax

> **Note:** PHP PSR coding standards dictate that the names of constants should be in uppercase and separated by underscores.

Learn about immutability and constants in PHP.

Getting Started

An Introduction to Functional Programming in PHP

Core Concepts: Functional Programming in PHP

Composition and Helper Functions

Error Handling in Functional Programming

Functors in PHP

Parallelization of Tasks in PHP

Recursion, Pattern Matching, and Property Testing

Phonebook Application — A Simple Project

Conclusion

Appendix

Immutability

What’s immutability?

Constants in PHP