Provides functions for iterable variables: is_iterable(), iterable_to_array()

1.4 2020-05-01 07:48 UTC

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Last update: 2020-07-31 00:16:12 UTC


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Iterable functions

Provides additional functions to work with iterable variables (even on PHP5.3+).


To check wether or not a PHP variable can be looped over in a foreach statement, PHP provides an is_iterable() function.

But this function only works on PHP7.1+.

This library ships a polyfill of this function for previous PHP versions.


var_dump(is_iterable(array('foo', 'bar'))); // true
var_dump(is_iterable(new DirectoryIterator(__DIR__))); // true
var_dump(is_iterable('foobar')); // false


PHP offers an iterator_to_array() function to export any iterator into an array.

But when you want to transform an iterable to an array, the iterable itself can already be an array.

When using iterator_to_array() with an array, PHP5 triggers a E_RECOVERABLE_ERROR while PHP7 throws a TypeError.

If you need an iterable-agnostic function, try our iterable_to_array():

var_dump(iterable_to_array(new ArrayIterator(array('foo', 'bar')))); // ['foo', 'bar']
var_dump(iterable_to_array(array('foo', 'bar'))); // ['foo', 'bar']


Useful when you have a Traversable type-hint, and you don't know wether or not your argument will be an array or an iterator.

If your variable is already an instance of Traversable (i.e. an Iterator, an IteratorAggregate or a Generator), the function simply returns it directly.

If your variable is an array, the function converts it to an ArrayIterator.


var_dump(iterable_to_traversable(array('foo', 'bar'))); // ArrayIterator(array('foo', 'bar'))
var_dump(iterable_to_traversable(new ArrayIterator(array('foo', 'bar')))); // ArrayIterator(array('foo', 'bar'))


Works like an array_map with an array or a Traversable.

$generator = function () {
    yield 'foo';
    yield 'bar';

foreach (iterable_map($generator(), 'strtoupper') as $item) {
    var_dump($item); // FOO, BAR


Works like an reduce with an iterable.

$generator = function () {
    yield 1;
    yield 2;

$reduce = static function ($carry, $item) {
    return $carry + $item;

    iterable_reduce($generator(), $reduce, 0))
); // 3


Works like an array_filter with an array or a Traversable.

$generator = function () {
    yield 0;
    yield 1;

foreach (iterable_filter($generator()) as $item) {
    var_dump($item); // 1

Of course you can define your own filter:

$generator = function () {
    yield 'foo';
    yield 'bar';

$filter = function ($value) {
    return 'foo' !== $value;

foreach (iterable_filter($generator(), $filter) as $item) {
    var_dump($item); // bar

Iterable factory

When you have an iterable type-hint somewhere, and don't know in advance wether you'll pass an array or a Traversable, just call the magic iterable() factory:

interface SomeInterface
     * Return an iterable list of items
     * @return iterable
    public function getItems(): iterable;

class MyService implements SomeInterface
     * @inheritdoc
    public function getItems(): iterable
        return iterable($this->someOtherService->findAll()):


It even accepts a null value (then converting it to an EmptyIterator).

You may add a filter callable and a map callable to make your life easier:

$data = [

$isFruit = function ($eatable) {
    return 'potato' !== $eatable;

var_dump(iterator_to_array(iterable($data)->filter($isFruit)->map('strtoupper'))); // ['banana', 'pineapple']


With composer (they'll be autoloaded):

composer require bentools/iterable-functions

Or manually:

require_once '/path/to/this/library/src/iterable-functions.php';

Unit tests