Lazzzy

Lazy collection library for PHP.

Wrap your iterables in a thin layer of pure lazyness, so they can be lazy-evaluated while you're being lazy too. :D

Why would I want that?

Collections are everywhere, but you usually don't want to materialize them in each operation. That's where lazyness come in handy. This allows you to map and filter in zero initialization time, for later evaluation when the time is right.

Features

• Convert anything into an iterable: arrays, iterators, functions, generators... you name it. [*]
• Map and filter with multiple functions on initialization, execute once on evaluation
• Handles infinite iterators

[*] planned

Compatibility

Lazzzy requires PHP 5.4 or higher for basic usage.

Installation

Just use composer to add to your project:

composer require xphere/lazzzy@dev

Usage

NOTE: Lazzzy is still in alpha, so don't rely on current methods. Just sayin'

Functions

Container::from(x) # lazy

Static function. Converts almost anything into an iterable. Returns a Container object wrapping the iterable.

use Lazzzy\Container;

$container = Container::from(range(0, 1000));

Container::getIterator()

Honors \IteratorAggregate interface so you can foreach over Containers.

Container::toAssoc() # not lazy

Iterates over the container, applying all transformations. Returns the resulting array.

use Lazzzy\Container;

$expected = ['a' => 0, 'b' => 1, 'c' => 2];
$container = Container::from($expected);

$values = $container->toAssoc();

$this->assertEquals($expected, $values);

Container::toArray() # not lazy

Like toAssoc method, but discards keys.

use Lazzzy\Container;

$expected = [0, 1, 2];
$values = ['a' => 0, 'b' => 1, 'c' => 2];
$container = Container::from($expected);

$values = $container->toAssoc();

$this->assertEquals($expected, $values);

Container::each(fn) # not lazy

Iterates over the container, executing fn on each iteration. Returns nothing.

use Lazzzy\Container;

$echo = function ($item) { echo $item, ', '; };
$container = Container::from(range(0, 5));

$container->each($echo);

/// Outputs "0, 1, 2, 3, " and returns nothing

Container::map(fn) # lazy (a -> b) -> [a] -> [b]

Calls fn transformation on each iteration of [a].

use Lazzzy\Container;

$expected = [0, 2, 4, 6];
$double = function ($item) { return $item * 2; };
$container = Container::from(range(0, 3))
    ->map($double)
;

$actual = $container->toArray();

$this->assertSame($expected, $actual);

Container::filter(fn) # lazy (a -> Bool) -> [a] -> [a]

Filters elements for which fn function returns truthy values.

use Lazzzy\Container;

$expected = [1, 3];
$odd = function ($item) { return $item % 2 === 1; };
$container = Container::from(range(0, 3))
    ->filter($odd)
;

$actual = $container->toArray();

$this->assertSame($expected, $actual);

Container::take(number) # lazy n -> [a] -> [a]

Takes n items from the iterator. n must be an integer greater than zero.

use Lazzzy\Container;

$expected = [0, 1];
$container = Container::from(range(0, 3))
    ->take(2)
;

$actual = $container->toArray();

$this->assertSame($expected, $actual);

Container::takeWhile(fn) # lazy n -> [a] -> [a]

Takes items while the condition fn is truthy.

use Lazzzy\Container;

$expected = [0, 1];
$notEqualsTwo = function ($item) { return $item !== 2; };
$container = Container::from(range(0, 3))
    ->takeWhile($notEqualsTwo)
;

$actual = $container->toArray();

$this->assertSame($expected, $actual);

More to come

• Container::skip(n)
• Container::skipUntil(fn)
• Container::fold(fn, x?)
• Container::foldr(fn, x?)
• Container::find(fn)
• Container::every(fn)
• Container::any(fn)
• Container::size()

Contributions

Please contribute with the project on GitHub

Author

Berny Cantos Contact: be@rny.cc GitHub: xPheRe Twitter: xPheRe

License

Lazzzy is licensed under the MIT License. See LICENSE file for full details.