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Primitives for functional programming in PHP
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README.md

Functional PHP: Functional primitives for PHP

Build Status

A set of functional primitives for PHP, heavily inspired by Scala’s traversable collection, Dojo’s array functions and Underscore.js

  • Works with arrays and everything implementing interface Traversable
  • Consistent interface: for functions taking collections and callbacks, first parameter is always the collection, than the callback. Callbacks are always passed $value, $index, $collection. Strict comparison is the default but can be changed
  • Calls 5.3 closures as well as usual callbacks
  • C implementation for performance but a compatible userland implementation is provided if you can’t install PHP extensions
  • All functions reside in namespace Functional to not raise conflicts with any other extension or library

TODO

  • Add iterator based generators: range(), repeat(), cycle(), ìncrement(), limit()
  • Add concat(array1, array2, ...), drop_while(), sort(), split_at(), slice(), without(), intersect()
  • Reverse iterate for last_index_of()
  • Fix performance of C impl. for iterators and last_index_of()/first_index_of()
  • Fix performance of C impl. for hash iterators and drop_first()

Installation

Install native extension

cd functional-php/
phphize
./configure
make
sudo make install

Use userland extension

<?php
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.

Overview

Functional\every() & Functional\invoke()

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

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

<?php
use Functional as F;

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

Functional\some()

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

<?php
use Functional as F;

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

Functional\none()

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

<?php
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()

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

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

<?php
use Functional as F;

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

Functional\drop_first() & Functional\drop_last()

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

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

<?php
use Functional as F;

$fn = function($user, $index, $collection) {
    return $index === 3;
};

// All users except the first three
F\drop_first($users, $fn);
// First three users
F\drop_last($users, $fn);

Functional\pluck()

Fetch a single property from a collection of objects or arrays.

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

<?php
use Functional as F;

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

Functional\partition()

Splits a collection into two by callback. Thruthy values come first

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

<?php
use Functional as F;

list($admins, $users) = F\partition($collection, function($user) {
    return $user->isAdmin();
});

Functional\group()

Splits a collection into groups by the index returned by the callback

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

<?php
use Functional as F;

$groupedUser = F\group($collection, $function($user) {
    return $user->getGroup()->getName();
});

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.

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

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

<?php
use Functional as F;

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

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

Functional\flatten()

Takes a nested combination of collections and returns their contents as a single, flat array. Does not preserve indexes.

array Functional\flatten(array|Traversable $collection)

<?php
use Functional as F;

$flattened = F\flatten(array(1, 2, 3, array(1, 2, 3, 4), 5));
// array(1, 2, 3, 1, 2, 3, 4, 5);

Functional\first_index_of()

Returns the first index holding specified value in the ccollection. Returns false if value was not found

array Functional\first_index_of(array|Traversable $collection, mixed $value)

<?php
use Functional as F;

// $index will be 0
$index = F\first_index_of(array('value', 'value'), 'value');

Functional\last_index_of()

Returns the last index holding specified value in the ccollection. Returns false if value was not found

array Functional\last_index_of(array|Traversable $collection, mixed $value)

<?php
use Functional as F;

// $index will be 1
$index = F\first_index_of(array('value', 'value'), 'value');

Functional\true() / Functional\false()

Returns true or false if all elements in the collection are strictly true or false

bool Functional\true(array|Traversable $collection)
bool Functional\false(array|Traversable $collection)

<?php
use Functional as F;

// Returns true
F\true(array(true, true));
// Returns false
F\true(array(true, 1));

// Returns true
F\false(array(false, false, false));
// Returns false
F\false(array(false, 0, null, false));

Functional\truthy() / Functional\falsy()

Returns true or false if all elements in the collection evaluate to true or false

bool Functional\truthy(array|Traversable $collection)
bool Functional\falsy(array|Traversable $collection)

<?php
use Functional as F;

// Returns true
F\truthy(array(true, true, 1, 'foo'));
// Returns false
F\truthy(array(true, 0, false));

// Returns true
F\falsy(array(false, false, 0, null));
// Returns false
F\falsy(array(false, 'str', null, false));

Functional\contains()

Returns true if given collection contains given element. If third parameter is true, the comparison will be strict

bool Functional\contains(array|Traversable $collection, mixed $value[, bool $strict = false])

<?php
use Functional as F;

// Returns true
F\contains(array('el1', 'el2'), 'el1');

// Returns false
F\contains(array('0', '1', '2'), 2);
// Returns true
F\contains(array('0', '1', '2'), 2, false);

Functional\zip()

Recombines arrays by index and applies a callback optionally

array Functional\zip(array|Traversable $collection1[, array|Traversable ...[, callable $callback]])

<?php
use Functional as F;

// Returns array(array('one', 1), array('two', 2), array('three', 3))
Functional\zip(array('one', 'two', 'three'), array(1, 2, 3));

// Returns array('one|1', 'two|2', 'three|3')
Functional\zip(
    array('one', 'two', 'three'),
    array(1, 2, 3),
    function($one, $two) {
        return $one . '|' . $two;
    }
);

Additional functions:

void Functional\each(array|Traversable $collection, callable $callback)
Applies a callback to each element

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

mixed Functional\first(array|Traversable $collection[, callable $callback])
Returns the first element of the collection where the callback returned true. If no callback is given, the first element is returned

mixed Functional\last(array|Traversable $collection[, callable $callback])
Returns the last element of the collection where the callback returned true. If no callback is given, the last element is returned

integer|float Functional\product(array|Traversable $collection, $initial = 1)
Calculates the product of all numeric elements, starting with $initial

integer|float Functional\ratio(array|Traversable $collection, $initial = 1)
Calculates the ratio of all numeric elements, starting with $initial

integer|float Functional\sum(array|Traversable $collection, $initial = 0)
Calculates the sum of all numeric elements, starting with $initial

integer|float Functional\difference(array|Traversable $collection, $initial = 0)
Calculates the difference of all elements, starting with $initial

integer|float|null Functional\average(array|Traversable $collection)
Calculates the average of all numeric elements

array Functional\unique(array|Traversable $collection[, callback $indexer[, bool $strict = true]])
Returns a unified array based on the index value returned by the callback, use $strict to change comparision mode

mixed Functional\maximum(array|Traversable $collection)
Returns the highest element in the array or collection

mixed Functional\minimum(array|Traversable $collection)
Returns the lowest element in the array or collection

Running the test suite

To run the test suite with the native implementation use php -c functional.ini $(which phpunit) tests/
To run the test suite with the userland implementation use php -n $(which phpunit) tests/

Mailing lists

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