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Learn Functional Programming in PHP

Transducers

Explore the concept of transducers as efficient data processing pipelines in PHP functional programming. Understand how to compose map and filter transducers to reduce intermediate list creation, enhancing performance and data transformation. This lesson will help you apply transducers to optimize chained operations like map and filter while maintaining functional purity.

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Overview

A transducer is a data processing pipeline. As the name suggests, transducers have a strong relationship with the fold (or reduce) operation. They’re particularly efficient because of their ability to carry multiple transformations and minimize instances of intermediate list creation. The impact of transducers is noticeable in situations where map and filter operations of various kinds follow each other, regardless of the order in which they appear. It’s worth noting that each transformation results in a new list.

The example below demonstrates this idea:

PHP
<?php
require __DIR__ . '/vendor/autoload.php';
use \Chemem\Bingo\Functional as f;
$square = f\map(fn ($x) => $x ** 2, range(1, 5));
                    
$even = f\filter(fn ($x) => $x % 2 == 0, $square);
                      
print_r($square);   // evaluates to [1, 4, 9, 16, 25]
print_r($even);     // evaluates to [4, 16]

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