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Primitives for functional programming in PHP
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Functional PHP: Functional primitives for PHP

  • Works with arrays and everything implementing interface Traversable
  • Consistent interface: first parameter is always the collection, than the callback. Callbacks always get value, key, collection passed
  • Calls 5.3 closures as well as traditional callbacks
  • C implementation for performance but compatible userland implementation is packaged if you can’t install PHP extensions
  • All functions reside in namespace Functional to not conflict with any other extension or library


  • Native implementation of Functional\pluck() shows slightly different behavior when dealing with private/protected properties
  • Implement Functional\curry() and related objects natively
  • Test reference handling
  • Add package.xml to build with pecl


Install native extension

cd functional-php/extension/
sudo make install

Use userland extension

include 'path/to/functional-php/src/Functional/_import.php';

Everytime you want to work with Functional PHP and not reference the fully qualified name, add use Functional as F; on top of your PHP file.



Functional\curry(callback $callback, [mixed $arg1, [mixed $arg2], ...])

use Functional as F;

$items = F\each(array('a1', 'a2'), F\curry('str_replace', 'a', 'b', F\arg(1))); // b1, b2

Functional\all() & Functional\invoke()

Functional\all(array|Traversable $collection, callable $callback)

Functional\invoke(array|Traversable $collection, string $methodName[, array $methodArguments])

use Functional as F;

// If all users are active, set them all inactive
if (F\all($users, function($user, $collectionKey, $collection) {return $user->isActive();})) {
    F\invoke($users, 'setActive', array(true));


Functional\any(array|Traversable $collection, callable $callback)

use Functional as F;

if (F\any($users, function($user, $collectionKey, $collection) use($me) {return $user->isFriendOf($me);})) {
    // One of those users is a friend of me


Functional\none(array|Traversable $collection, callable $callback)

use Functional as F;

if (F\none($users, function($user, $collectionKey, $collection) {return $user->isActive();})) {
    // Do something with a whole list of inactive users

Functional\reject() & Functional\select()

Functional\select(array|Traversable $collection, callable $callback)

Functional\reject(array|Traversable $collection, callable $callback)

use Functional as F;

$fn = function($user, $collectionKey, $collection) {
    return $user->isActive();
$activeUsers = F\select($users, $fn);
$inactiveUsers = F\reject($users, $fn);


Fetch a single property from a collection of objects.

Functional\pluck(array|Traversable $collection, string $propertyName)

use Functional as F;

$names = F\pluck($users, 'name');

Functional\reduce_left() & Functional\reduce_right()

Applies a callback to each element in the collection and reduces the collection to a single scalar value. Functional\reduce_left() starts with the first element in the collection, while Functional\reduce_right() starts with the last element.

Functional\reduce_left(array|Traversable $collection, callable $callback[, $initial = null]) Functional\reduce_right(array|Traversable $collection, callable $callback[, $initial = null])

use Functional as F;

// $sum will be 64 (2^2^3)
$sum = F\reduce_left(array(2, 3), function($value, $key, $collection, $reduction) {
    return $reduction ^ $value;
}, 2);

// $sum will be 512 (2^3^2)
$sum = F\reduce_right(array(2, 3), function($value, $key, $collection, $reduction) {
    return $reduction ^ $value;
}, 2);

Additional functions:

  • Functional\each(array|Traversable $collection, callable $callback) Applies a callback to each element
  • Functional\map(array|Traversable $collection, callable $callback) Applies a callback to each element in the collection and collects the return value
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