mpetrovich / dash

A functional programming library for PHP. Inspired by Underscore, Lodash, and Ramda.

Dash  

A functional programming library for PHP. Inspired by Underscore, Lodash, and Ramda.

$avgMaleAge = Dash\chain([
	['name' => 'John', 'age' => 12, 'gender' => 'male'],
	['name' => 'Jane', 'age' => 34, 'gender' => 'female'],
	['name' => 'Pete', 'age' => 23, 'gender' => 'male'],
	['name' => 'Mark', 'age' => 11, 'gender' => 'male'],
	['name' => 'Mary', 'age' => 42, 'gender' => 'female'],
])
->filter(['gender', 'male'])
->map('age')
->average()
->value();

echo "Average male age is $avgMaleAge.";

Jump to:

• Functions / Operations
• Highlights
• Why use Dash?
• Installation
• Usage
  • Standalone
  • Chaining
  • Supported data types
  • Currying
  • Lazy evaluation
  • Custom operations
  • Tips
• Changelog
• Roadmap
• Contributing

Operations

View full list of operations here

Highlights

• Many data types supported: arrays, objects, generators (coming soon), Traversable, DirectoryIterator, and more
• Chaining
• Currying
• Lazy evaluation
• Custom operations
• Well-tested: Comprehensive tests with nearly 3,000 test cases and 100% code coverage

Why use Dash?

PHP's built-in array_* functions are limited, difficult to compose, inconsistent, and don't work across many data types.

For instance, let's say we want to find the average age of males in this list:

$people = [
	['name' => 'John', 'age' => 12, 'gender' => 'male'],
	['name' => 'Jane', 'age' => 34, 'gender' => 'female'],
	['name' => 'Pete', 'age' => 23, 'gender' => 'male'],
	['name' => 'Mark', 'age' => 11, 'gender' => 'male'],
	['name' => 'Mary', 'age' => 42, 'gender' => 'female'],
];

Using PHP's built-in in functions, we might write something like this:

$males = array_filter($people, function ($person) {
	return $person['gender'] === 'male';
});
$avgMaleAge = array_sum(array_column($males, 'age')) / count($males);

Dash makes common data transformation operations simpler:

$avgMaleAge = Dash\chain($people)
	->filter(['gender', 'male'])
	->map('age')
	->average()
	->value();

This is just a tiny subset of what Dash can do. See the full list of operations here.

Installation

Requires PHP 7.4+

composer require mpetrovich/dash

Usage

Dash operations are pure functions that can be used alone or chained together.

Standalone

Operations can be called as namespaced functions:

Dash\map([1, 2, 3], function ($n) { return $n * 2; });  // === [2, 4, 6]

or as static methods:

use Dash\Dash;

Dash::map([1, 2, 3], function ($n) { return $n * 2; });  // === [2, 4, 6]

Dash\_ can also be used as an alias for Dash\Dash:

use Dash\_;

_::map([1, 2, 3], function ($n) { return $n * 2; });  // === [2, 4, 6]

Chaining

Multiple operations can be chained in sequence using chain(). Call value() to return the final value.

$result = Dash\chain([1, 2, 3, 4, 5])
	->filter('Dash\isOdd')
	->map(function ($n) { return $n * 2; })
	->value();

// $result === [2, 6, 10]

To explicitly convert the value to an array or stdClass, use arrayValue() or objectValue() respectively:

$result = Dash\chain(['a' => 1, 'b' => 2, 'c' => 3])
	->filter('Dash\isOdd')
	->mapValues(function ($n) { return $n * 2; })
	->objectValue();

// $result === (object) ['a' => 2, 'c' => 6]

For convenience, Dash\chain() can be aliased to a global function using addGlobalAlias(). It only needs to be called once during your application bootstrap:

// In your application bootstrap:
Dash::addGlobalAlias('__');

// Elsewhere:
$result = __([1, 2, 3, 4, 5])
	->filter('Dash\isOdd')
	->map(function ($n) { return $n * 2; })
	->value();

Sometimes you don't need the return value of the chain. However, the chain isn't processed until value() is called. For semantic convenience, run() is also an alias for value():

$chain = Dash\chain(range(1, 5))
	->reverse()
	->each(function ($n) {
		echo "T-minus $n...\n";
		sleep(1);
	});

// Nothing echoed yet

$chain->value();
// or
$chain->run();

// Echoes each of the following lines 1 second apart:
// T-minus 5...
// T-minus 4...
// T-minus 3...
// T-minus 2...
// T-minus 1...

Supported data types

Dash can work with a wide variety of data types, including:

• arrays
• objects (eg. stdClass)
• generators (still in development)
• anything that implements the Traversable interface
• DirectoryIterator, which is also a Traversable but cannot normally be used with iterator_to_array() due to a PHP bug. Dash works around this transparently.

Examples

With an array:

Dash\chain([1, 2, 3, 4])
	->filter('Dash\isEven')
	->map(function ($value) {
		return $value * 2;
	})
	->value();
// === [4, 8]

With an object:

Dash\chain((object) ['a' => 1, 'b' => 2, 'c' => 3, 'd' => 4])
	->filter('Dash\isOdd')
	->keys()
	->join(', ')
	->value();
// === 'a, c'

With a Traversable:

Dash\chain(new ArrayObject(['a' => 1, 'b' => 2, 'c' => 3, 'd' => 4]))
	->pick(['b', 'c'])
	->values()
	->sum()
	->value();
// === 5

With a DirectoryIterator:

$iterator = new FilesystemIterator(__DIR__, FilesystemIterator::SKIP_DOTS);

$filenames = Dash\chain($iterator)
	->reject(function ($fileinfo) {
		return $fileinfo->isDir();
	})
	->map(function ($fileinfo) {
		return pathinfo($fileinfo)['filename'];
	})
	->value();

Currying

curry() and related operations can be used to create curried functions from any callable:

function listThree($a, $b, $c) {
	return "$a, $b, and $c";
}

$listThree = Dash\curry('listThree');
$listTwo = $listThree('first');
$listTwo('second', 'third');  // === 'first, second, and third'

Most Dash functions have a curried version that accepts input data as the last parameter instead of as the first. Curried versions are located in the Dash\Curry namespace:

Dash\chain([
	'a' => 3,
	'b' => '3',
	'c' => 3,
	'd' => 3.0
])
->filter(Dash\Curry\identical(3))
->value();
// === ['a' => 3, 'c' => 3]

Similarly, partial() and related operations can be used to create partially-applied functions:

$greet = function ($greeting, $name) {
	return "$greeting, $name!";
};

$sayHello = Dash\partial($greet, 'Hello');
$sayHowdy = Dash\partial($greet, 'Howdy');

$sayHello('Mark');  // === 'Hello, Mark!'
$sayHowdy('Jane');  // === 'Howdy, Jane!'

Lazy evaluation

Chained operations are not evaluated until value() or run() is called. Furthermore, the input data can be changed and evaluated multiple times using with(). This makes it simple to create reusable chains:

$chain = Dash\chain()
	->filter('Dash\isOdd')
	->map(function ($n) { return $n * 2; });

$chain->with([1, 2, 3])->value();  // === [2, 6]
$chain->with([4, 5, 6, 7])->value();  // === [10, 14]

Chains can also be cloned and extended:

// …continued from above
$clone = clone $chain;
$clone->map(function ($n) { $n + 1; })
$clone->value();  // === [11, 15]

// The original chain is untouched
$chain->value();  // === [10, 14]

When value() is called, the result is cached until the chain is modified or the input is changed using with().

Custom operations

Custom operations can be added, retrieved, and removed using setCustom(), getCustom(), and unsetCustom(), respectively. Dash\custom() is also an alias for Dash::getCustom():

Dash::setCustom('triple', function ($n) { return $n * 3; });

// Standalone
Dash::triple(4);  // === 12

// Chained
Dash\chain([1, 2, 3])
	->sum()
	->triple()
	->value();  // === 18

// As an argument
Dash\chain([1, 2, 3])
	->map('Dash\Dash::triple')
	->value();  // === [3, 6, 9]

// As an argument using the Dash::getCustom() method
Dash\chain([1, 2, 3])
	->map(Dash::getCustom('triple'))
	->value();  // === [3, 6, 9]

// Using the Dash\custom() operation
Dash\chain([1, 2, 3])
	->map(Dash\custom('triple'))
	->value();  // === [3, 6, 9]

Dash::unsetCustom('triple');

When chained, the current input is passed as the first parameter to the custom operation:

Dash::setCustom('divide', function($numerator, $denominator) { return $numerator / $denominator; });

Dash\chain(6)->divide(2)->value();  // === 2

Tips

If you find that Dash doesn't have an operation that you need, fear not. Custom logic can be added without giving up Dash chaining or other features. The simplest way to integrate missing operations is via the Dash\thru() operation, which allows custom logic to modify and seamlessly pass through its results to the next step in the chain.

For example, suppose we want to use array_change_key_case() and keep the usual Dash chaining semantics. With thru(), it's simple:

$result = Dash\chain(['one' => 1, 'two' => 2, 'three' => 3])
	->filter('Dash\isOdd')
	->thru(function($input) {
		return array_change_key_case($input, CASE_UPPER);
	})
	->keys()
	->value();

// $result === ['ONE', 'THREE']

Alternatively, if you find yourself needing to use array_change_key_case() often, it may be better to add a new custom operation:

Dash::setCustom('keyCase', function ($input, $case) {
	return array_change_key_case($input, $case);
});

which you can then use like any other chainable Dash method:

$result = Dash\chain(['one' => 1, 'two' => 2, 'three' => 3])
	->filter('Dash\isOdd')
	->keyCase(CASE_UPPER)
	->keys()
	->value();

// $result === ['ONE', 'THREE']

Feedback

Found a bug or have a suggestion? Please create a new GitHub issue. We want your feedback!

dash's Issues

Add Dash\Dash class as an alias for Dash\_

It's good sugar

Cannot use curry right inside chain properly.

$sub = function($a, $b) { return $a - $b; };
$cSub = _::curry($sub);
$cSub(9)(5); //result = 4
_::setCustom('sub', $cSub );
  
$flSub = _::curryRight($sub);
$flSub(9)(5); // result = -4
_::setCustom('flsub', $flSub );

_::chain(9)->sub(5)->run(); //result = 4
_::chain(9)->flsub(5)->run();  //result = 4

On the last line shouldn't it be "-4" or am I missing something?

Add unique()

Support generators

Operators like filter and map take an iterable but return an array. All values of the iterable have to be iterated during evaluation. The following example will run out of memory because ints is an infinite iterable:

function ints() {
    $counter = 0;
    while (true) {
        yield $counter;
        ++$counter;
    }
}

$result = Dash\_chain(ints())
    ->filter('Dash\isEven')
    ->take(3)
    ->join(', ')
    ->value();

The same works fine if you use iterables as intermediate results like nikic/iter does

$result = iter\join(', ',
    iter\take(3,
        iter\filter('Dash\isEven',
            ints())));

Is there a way to make union nonunique ? I need the duplicates values for further calculations.

I need the mathematical set theory union basically.

Dash::union (
[1, 3, 5],
[1 ,3 ,7 ],
[7, 8] );

Expected output 1,3,5,1,3,7,7,8

version 1.0.0

Is there anything against releasing version 1.0.0 (see How do I know when to release 1.0.0?)?

Add flatten()

Add clamp()

clamp($v, $min, $max) returns $min if $v < $min
                              $max if $v > $max
                              $v if $min <= $v <= $max

Add function compose

Hey, Thanks for new features you added so far.
Still I need compose function, It Will be great if you add it.
Ramda Compose

Accept single values for comparison in filter() and reject()

It could be easier to reject items that strictly equal a given static value. Example:

Dash\filter(
    ['a', 'b', 'c', 'd, 'c', 'e'],
    ['c']
);
// === ['a', 'b', 'd', 'e']

Fatal error on chain method join

Hey
my code is

$content = _::chain($input)
    ->filter(function ($i) {
      return $i['action_name'] === "type1" ? true : false;
    })
    ->map(function ($i) {
      return getHTML($i['banner']);
    })
    ->join('')
    ->value();

  echo $content;

I used join in chain but i get fatal error

PHP Fatal error: Uncaught InvalidArgumentException: Dash\\join expects iterable or stdClass or null but was given string

Global functions shouldn't take precedence over array keys or object properties

When accessing array keys or object properties that share the same name as a global function (eg. abs), the global function is referenced/returned instead of the appropriate array/object value. This affects a number of operations including get(), map(), and property().

Test cases

$this->assertSame(
	['a', 'b', 'c'],
	Dash\map([
		['abs' => 'a'],
		['abs' => 'b'],
		['abs' => 'c'],
	], 'abs')
);

$this->assertSame(
	'value',
	Dash\get(['abs' => 'value'], 'abs')
);

$this->assertSame(
	'value',
	call_user_func(Dash\property('abs'), ['abs' => 'value'])
);

Dash\sort() doesn't sort decimal values correctly

usort() doesn't work natively with decimal values. Details: https://stackoverflow.com/questions/16520000/usort-issue-with-decimal-numbers

Add flatMap()

curry() breaks with array callables

If curry() is called with an array-style callable (eg. [$this, 'sum']), an exception is thrown:

TypeError: ReflectionFunction::__construct() expects parameter 1 to be string, array given

Test case

class curryTest extends PHPUnit_Framework_TestCase
{
	public function sum($a, $b)
	{
		return $a + $b;
	}

	public function test()
	{
		$callable = [$this, 'sum'];
		$curried = Dash\curry($callable);
		$curried = $curried(1);
		$this->assertSame(3, $curried(2));
	}
}

Is the example for 'curryRight' correct?

I mean the example is similar to 'curry'. Shouldn't curryRight's arguments applied in reverse order?

PHP 8 error: method_exists(): Argument #1 ($object_or_class) must be of type object|string, array given

There is a type error when using the operator get for PHP8.

Problem:
src/hasDirect.php in method_exists at line 36

dash/src/hasDirect.php

Lines 27 to 37 in bd6ec10

	function hasDirect($input, $key)
	{
	if (!is_string($key) && !is_numeric($key) && !is_null($key)) {
	return false;
	}
	return is_array($input) && array_key_exists($key, $input)
	|| is_object($input) && property_exists($input, $key)
	|| $input instanceof \ArrayAccess && $input->offsetExists($key)
	|| method_exists($input, $key);
	}

Add mapMerge()

See https://www.nurkiewicz.com/2019/03/mapmerge-one-method-to-rule-them-all.html

Add Dash\mapResult($iterable, $path, $default)

It should return something to the effect of:

Dash\map($iterable, Dash\Curry\result($path, $default));

Example:

$array = $array = [
   ['fn' => function() { ... }],
   ['fn' => function() { ... }],
   ['fn' => function() { ... }],
];
$fns = Dash\map($array, 'fn');
$results = Dash\mapResult($array, 'fn');