README

ComposeMixins is a tiny but extendable PHP library for function composition.

Installation

# in your project root
composer require reasno/compose-mixins

Examples

use function Reasno\Helpers\composeMixins;
use Reasno\Helpers\Recipe;

$c = composeMixins(new Recipe('pipe'), /* callable */ $a, /* callable */ $b);
$result = $c($input); //Use the composed function

$c becomes a composition of function $a and function $b. You can verify it with the following snippet.

$result1 = $c($input);
$result2 = $a($b($input));

var_dump($result1 === $result2); //true

API

function composeMixins(Recipe $recipe, callable ...$mixins)

Recipes

This library comes with a few (most frequently used) built in recipes. These recipes define how functions are composed together.

pipe: h(x) = g(f(x))
map: h(list) = array_map(g, (array_map(f, list)))
all: returns true if all functions (eg. f(x), g(x)...) return true.
any: returns true if any function returns true.

To use any recipe, create new instance with their names passed into constructor.

new Recipe('map');

You can create new recipes on the fly. Just pass in a closure.

/* use a different handler each time the composed function is called */
$r = Recipe::fromCallable(function(...$fns){
	static $i = 0;
	return function($input) use (&$i, $fns){
		try{
			return $fns[$i++]($input);
		} catch( Error $e ){
			return null;
		}

	};
});

You can define your own RecipeHandlers in your own code, and pass it to the recipe constructor.

Class MyRecipeHandler{
	//...
}
$CustomRecipe = new Recipe('fancy', ['handler' => 'MyRecipeHandler']);

Please take a look at RecipeHandler.php in this library to learn how to write your own handlers.

Caveat

Functions composed with map and collapse recipes also accept Traversable as input.
For all and any recipes, all functions are always evaluated regardless of their return values.

Testing

PHPUnit is overkill for this project. To do a simple test, execute php tests/composeMixinsTest.php and see if all assertions pass.

reasno / compose-mixins

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