README

• Online documentation
• GitHub repository

Features

• The most complete port of .NET LINQ to PHP, with many additional methods.
• Lazy evaluation, error messages and other behavior of original LINQ.
• Detailed PHPDoc and online reference based on PHPDoc for all methods. Articles are adapted from original LINQ documentation from MSDN.
• 100% unit test coverage.
• Best performance among full-featured LINQ ports (YaLinqo, Ginq, Pinq), at least 2x faster than the closest competitor, see performance tests.
• Callback functions can be specified as arrow functions (fn($v) => $v), first-class callables (strnatcmp(...)) or any other PHP callables.
• Keys are as important as values. Most callback functions receive both values and the keys; transformations can be applied to both values and the keys; keys are never lost during transformations, if possible.
• SPL interfaces Iterator, IteratorAggregate etc. are used throughout the code and can be used interchangeably with Enumerable.
• Redundant collection classes are avoided, native PHP arrays are used everywhere.
• Composer support (package on Packagist).
• No external dependencies.

Implemented methods

Some methods had to be renamed, because their names are reserved keywords. Original methods names are given in parenthesis.

• Generation: cycle, emptyEnum (empty), from, generate, toInfinity, toNegativeInfinity, matches, returnEnum (return), range, rangeDown, rangeTo, repeat, split;
• Projection and filtering: cast, ofType, select, selectMany, where;
• Ordering: orderBy, orderByDescending, orderByDir, thenBy, thenByDescending, thenByDir;
• Joining and grouping: groupJoin, join, groupBy;
• Aggregation: aggregate, aggregateOrDefault, average, count, max, maxBy, min, minBy, sum;
• Set: all, any, append, concat, contains, distinct, except, intersect, prepend, union;
• Pagination: elementAt, elementAtOrDefault, first, firstOrDefault, firstOrFallback, last, lastOrDefault, lastOrFallback, single, singleOrDefault, singleOrFallback, indexOf, lastIndexOf, findIndex, findLastIndex, skip, skipWhile, take, takeWhile;
• Conversion: toArray, toArrayDeep, toList, toListDeep, toDictionary, toJSON, toLookup, toKeys, toValues, toObject, toString;
• Actions: call (do), each (forEach), write, writeLine.

In total, more than 80 methods.

Example

Process sample data:

// Data
$products = [
    ['name' => 'Keyboard', 'catId' => 'hw', 'quantity' => 10, 'id' => 1],
    ['name' => 'Mouse', 'catId' => 'hw', 'quantity' => 20, 'id' => 2],
    ['name' => 'Monitor', 'catId' => 'hw', 'quantity' => 0, 'id' => 3],
    ['name' => 'Joystick', 'catId' => 'hw', 'quantity' => 15, 'id' => 4],
    ['name' => 'CPU', 'catId' => 'hw', 'quantity' => 15, 'id' => 5],
    ['name' => 'Motherboard', 'catId' => 'hw', 'quantity' => 11, 'id' => 6],
    ['name' => 'Windows', 'catId' => 'os', 'quantity' => 666, 'id' => 7],
    ['name' => 'Linux', 'catId' => 'os', 'quantity' => 666, 'id' => 8],
    ['name' => 'Mac', 'catId' => 'os', 'quantity' => 666, 'id' => 9],
];
$categories = [
    ['name' => 'Hardware', 'id' => 'hw'],
    ['name' => 'Operating systems', 'id' => 'os'],
];

// Put products with non-zero quantity into matching categories;
// sort categories by name;
// sort products within categories by quantity descending, then by name.
$result = from($categories)
    ->orderBy(fn($cat) => $cat['name'])
    ->groupJoin(
        from($products)
            ->where(fn($prod) => $prod['quantity'] > 0)
            ->orderByDescending(fn($prod) => $prod['quantity'])
            ->thenBy(fn($prod) => $prod['name'], 'strnatcasecmp'),
        fn($cat) => $cat['id'],
        fn($prod) => $prod['catId'],
        fn($cat, $prods) => [
            'name' => $cat['name'],
            'products' => $prods
        ]
    );

// More verbose syntax with argument names:
$result = Enumerable::from($categories)
    ->orderBy(keySelector: fn($cat) => $cat['name'])
    ->groupJoin(
        inner: from($products)
            ->where(predicate: fn($prod) => $prod['quantity'] > 0)
            ->orderByDescending(keySelector: fn($prod) => $prod['quantity'])
            ->thenBy(keySelector: fn($prod) => $prod['name'], comparer: strnatcasecmp(...)),
        outerKeySelector: fn($cat) => $cat['id'],
        innerKeySelector: fn($prod) => $prod['catId'],
        resultSelectorValue: fn($cat, $prods) => [
            'name' => $cat['name'],
            'products' => $prods
        ]
    );

print_r($result->toArrayDeep());

Output (compacted):

Array (
    [hw] => Array (
        [name] => Hardware
        [products] => Array (
            [0] => Array ( [name] => Mouse       [catId] => hw [quantity] =>  20 [id] => 2 )
            [1] => Array ( [name] => CPU         [catId] => hw [quantity] =>  15 [id] => 5 )
            [2] => Array ( [name] => Joystick    [catId] => hw [quantity] =>  15 [id] => 4 )
            [3] => Array ( [name] => Motherboard [catId] => hw [quantity] =>  11 [id] => 6 )
            [4] => Array ( [name] => Keyboard    [catId] => hw [quantity] =>  10 [id] => 1 )
        )
    )
    [os] => Array (
        [name] => Operating systems
        [products] => Array (
            [0] => Array ( [name] => Linux       [catId] => os [quantity] => 666 [id] => 8 )
            [1] => Array ( [name] => Mac         [catId] => os [quantity] => 666 [id] => 9 )
            [2] => Array ( [name] => Windows     [catId] => os [quantity] => 666 [id] => 7 )
        )
    )
)

Versions

Usage

Add to composer.json:

{
    "require": {
        "athari/yalinqo": "^2.0"
    }
}

Add to your PHP script:

require_once 'vendor/autoloader.php';
use \YaLinqo\Enumerable;

// 'from' can be called as a static method or via a global function shortcut
Enumerable::from([1, 2, 3]);
from([1, 2, 3]);

Legacy information

Legacy features

• (Versions 1.0−2.5) Callback functions can be specified as "string lambdas" using various syntaxes:
  • '"$k = $v"' (implicit $v and $k arguments, implicit return)
  • '$v ==> $v + 1' (like a modern arrow function, but without fn and with a longer arrow)
  • '($v, $k) ==> $v + $k' (explicit arguments, implicit return)
  • '($v, $k) ==> { return $v + $k; }' (explicit arguments, explicit return within a block)

Note

Before arrow functions were added in PHP 7.4, the choice was between the ridiculously verbose anonymous function syntax (function ($value) { return $value['key']; }) and rolling your own lambda syntax (like $v ==> $v["key"]). This is why "string lambdas" were a necessity at the time.

Caution

When using legacy versions of YaLinqo and PHP, you:

1. MUST NOT use user-provided strings to construct string lambdas;
2. SHOULD NOT dynamically construct string lambdas in general.

When all your string lambdas are single-quoted string constants, there's no security risk in using them. If you're still paranoid about eval, just never use string lambdas.

License

Simplified BSD License
Copyright © 2012–2025, Alexander Prokhorov

Links

YaLinqo Articles

• CodeProject (English):

  • LINQ for PHP comparison: YaLinqo, Ginq, Pinq — performance comparison of full-featured LINQ ports, with some additional information.

• Habrahabr (Russian):

  • Comparison of old LINQ libraries — comparison of LINQ for PHP, Phinq, PHPLinq and Plinq, also Underscore.php.
  • YaLinqo 1.0 with updated comparison — explanation of architecture and design decisions.
  • YaLinqo 2.0 — switch to PHP 5.5 with generators support and related changes.
  • LINQ for PHP: speed matters — performance comparison of full-featured LINQ ports (YaLinqo, Ginq, Pinq).

• Other (English):

  • Tute Wall: How to use Linq in PHP by Mr. X — a series of posts covering basic usage of YaLinqo.

Related projects

• linq.js — LINQ for JavaScript. The one and only complete port of .NET LINQ to JavaScript.
• Underscore.js — library for functional programming in JavaScript. Similar to LINQ, but different method names and no lazy evaluation.
• Underscore.php — port of Underscore.js to PHP.
• RxPHP — reactive (push) counterpart of the active (pull) LINQ, port of Rx.NET.
• YaLinqoPerf — collection of performance tests comparing raw PHP, array functions, YaLinqo, YaLinqo with string lambdas, Ginq, Ginq with property accessors, Pinq.

PHP

• Dead PHP RFCs:
  • Short Closures 2.0 — support for multi-statement arrow functions declined, 2 votes short.
  • Add array_group function — grouping won't be optimized by using a built-in function.
  • Partial function application — imagine pipe operator being actually useful... nah, not happening.
  • Pipe operator v3 (v2, v1) — took 3 RFCs and 10 years, but we've finally arrived at... the least useful and the most verbose pipe syntax on the planet... yay?