Lazy array function chains inspired in Rust

0.0.2 2020-08-01 23:13 UTC

This package is auto-updated.

Last update: 2021-07-04 20:09:35 UTC


Lazy array function chains inspired by Rust

Design goals

  1. Be lazy (as in Lazily evaluated)
  2. Have a similar interface to Rust's Iterator
  3. Leverage static code analyzers to validate type correctness


composer require nicofff/lazy-iter

PHP 7.4 required


require_once __DIR__ . '/vendor/autoload.php';
use LazyIter\LazyIter;
use LazyIter\Helpers\Generators\Range;

// Calculate the sum of all the squared numbers below a million
$sum_squares_under_a_million = 
    (new LazyIter(Range::rangeFrom(1))) // Start with an iterator over all positive numbers
	->map(fn($n) => pow($n,2) ) // Square each one of them
	->take_while(fn($n) => $n < 1_000_000 ) // Stop once we reach a million
	->sum(); // sum them

echo $sum_squares_under_a_million;

Project status

Methods implemented (based on Rust's Iterator Trait)

  • all
  • any
  • chain
  • collect
  • count
  • cycle
  • filter
  • fold
  • for_each
  • last
  • map
  • nth
  • skip
  • sum
  • take
  • take_while

Type Enforcement

Currently using PHPStan for type validation. Check type_tests for a list of things it caches for each method


->for_each(function(string $n): void{
	echo $n;


Parameter #1 $callable of method                                      
         LazyIter\LazyIter<int,int>::for_each() expects callable(int): mixed,  
         Closure(string): void given. 

Accepting contributions to support Phan and Psalm