Immutable and persistent data structures for PHP.

Life would be a lot simpler if we had immutable data structures. Code would be easier to understand, easy to test and free of side-effects. Being immutable is not all, these data structures must be efficient. By making them persistent, collections reuse internal structure to minimize the number of operations needed to represent altered versions of an instance of a collection.

Add the following to your composer.json file

{
    "require": {
        "keyvanakbary/medusa": "*"
    }
}

Update the vendor libraries

curl -s http://getcomposer.org/installer | php
php composer.phar install

<?php

include 'vendor/autoload.php';

$s = Medusa\Stack::createEmpty();

$s1 = $s->push(1);
$s2 = $s1->pop();
echo $s1->peek();//1
echo $s2->peek();//Runtime exception

<?php
include 'vendor/autoload.php';

$q = Medusa\Queue::createEmpty();

$q1 = $q->enqueue(1);
$q2 = $q1->dequeue();
echo $q1->peek();//1
echo $q2->peek();//Runtime exception