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

# Terminology used in the course

Functional programming is a vast field and has an elaborate lexicon. Below are definitions for some of the more prominent functional programming ideas discussed throughout the course:

- **Turing machine:** An abstract computation model with memory that manipulates the contents of the memory in accordance with a set of rules.

- **Function:** A relation that associates elements of a domain, or a set, to those of a codomain, or another set.

- **Arity:** The number of arguments a function accepts.

- **Lambda calculus:** A mathematical system developed by Alonzo Church premised on using abstraction and function application for computation that involves variable binding and substitution.

- **Abstraction:** The detachment of mathematical ideas from particular situations and generalization of said concepts for a variety of use-cases.

- **Function application:** The act of applying a function to a value from a set of applicable values to generate a result in a set of possible return values.

- **Category theory:** The study of the mathematical notion of categories, or subtle algebras that abstract real-life concepts.

- **First-class function support:** A property of programming languages that enables support for the usage of functions in various fashions akin to variables usage, treating them as first-class citizens.

- **Pure function:** A function with no side effects or side causes.

- **Referential transparency:**  The barometer for function purity. This is the proof of whether a function always evaluates to the same output given the same input.

- **PHP userland:** A buzzword for all the functions, variables, and objects contained in the PHP core distribution.

- **Variadic functions:** Callable units of indefinite arity.

- **Boolean short-circuiting:** Instead of evaluating all terms of a boolean expression, stopping (or short-circuiting) immediately after evaluating a subexpression that determines the truth or falsity of the expression.

- **Functor:** A type class with contents that can be mapped over and adheres to the laws of identity and composition.

- **Fuzzing:** A testing technique that involves feeding multiple inputs, mostly random and likely erroneous, into a program.

- **Monad:** A versatile functor built atop polymorphic concepts that adheres to the laws of right-identity, left-identity, and associativity.

- **Type class:** A composite data type that supports operator overloading.

- **Recursion:** A function calling itself.

- **Pattern matching:** A top-to-bottom, left-to-right algorithm to check a value against a sequence of tokens.

- **Property testing:** A condition achievable by a threaded program that allows it to coexist in a threaded environment.

- **Thread:** A dispatchable unit of work within a process.
- **Transducer:** A composable higher-order algorithmic transformation usable on list structures.

- **Message broker:** An architecture premised on relaying messages from senders to receivers through a messaging protocol.

- **Job worker:** A script that usually runs in the background and processes message queue data.

- **Message queue:** A queue optimized for asynchronous data passing between producers and consumers.

- **Temporal coupling:** A situation in which two or more class methods, closely dependent on each other, require invocation in a particular order.

- **Thread safety:** A condition achievable by a threaded program that allows it to exist in a threaded environment.

- **Union type:** A composite algebraic data type (ADT) composed of multiple subtypes.


Learn the definitions of some prominent functional programming ideas discussed in the course.


Terminology

Learn the definitions of some prominent functional programming ideas discussed in the course.

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

Terminology

Terminology used in the course