Functional programming

Byte-sized functional programming: Pure functions encourage small code

One of the many pieces of advice for a long-term sustainable code base is to keep code small. The larger a code base is, the more effort it takes to understand all the moving parts. Your brain can only keep so much mental model of your code in it at once, and if the code you're looking at is too large then what you can fit in your own "active memory" at once then you will have an increasingly hard time understanding it.

Most useful applications tend to grow larger than what the typical human can fit in their active memory, however, so you need a way to break up your code so you can load a relevant piece into your brain at once to understand and debug it. Usually that takes the form of encapsulation, coupling, cohesion, and other common object-oriented vernacular.

But what about just a pure function?

A pure function is a function that:

Larry 6 July 2020 - 5:13pm

Announcing "Thinking Functionally in PHP"

Submitted by Larry on 20 May 2020 - 9:16am

Calling all PHP developers! Want to wrap your brain around functional programming? Are you sick of reading tutorials about this magic "monad" thing but having no idea how to read Haskell? Then this book is for you.

Announcing Thinking Functionally in PHP, by yours truly, available now on LeanPub.

PHP, functional programming, and category theory, all in one short volume

PHP 7.4's introduction of short-lambdas is a game changer for functional PHP. While it doesn't make anything new possible, it makes a lot of things suddenly practical. That's what this book is about: What is now practical to do in PHP in terms of functional programming.

Type Matching in PHP

Submitted by Larry on 2 February 2020 - 1:46pm

One of the nice features of Rust is the match keyword. match is similar to switch, but with two key differences:

  1. It requires an exhaustive match, that is, every possible value must be accounted for or a default must be provided.
  2. match is an expression, meaning you can assign the return value of one of its branches to a variable.

That makes match extremely useful for ensuring you handle all possibilities of an enumerated type, say, if using an Optional or Either for error handling. Which... is something I've been experimenting with in PHP.

It's hard to make a PHP equivalent of match that forces an exhaustive match, as PHP lacks enumerated types. However, emulating an expression match turns out to be pretty easy in PHP 7.4, and kind of pretty, too.

The Functional PHP tour

Submitted by Larry on 13 April 2014 - 11:35pm

Ever heard of functional programming? Not procedural programming, but actual functional programming. Probably, as some fancy academic thing that no one really uses, right?

Did you know you can do it in PHP, too? It's true. In fact, I'll be speaking about it four times in the next couple of weeks!

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