Implementing a queue

We can implement a queue using Tarsana and the built-in functions for list operations. We will use the array for queue representation as well using this code:

require __DIR__ . '/vendor/autoload.php'; 

use Tarsana\Functional as F; 

$queue = []; 

$enqueue = F\append(F\__(), F\__()); 
$head = F\head(F\__()); 
$dequeue = F\tail(F\__()); 

$queue = $enqueue(1, $queue); 
$queue = $enqueue(2, $queue); 
$queue = $enqueue(3, $queue); 

echo "Queue is ".F\toString($queue)."\n"; 

$item = $head($queue); 
$queue = $dequeue($queue); 

echo "Dequeue-ed item: ".$item."\n"; 
echo "Queue is ".F\toString($queue)."\n"; 

$queue = $enqueue(4, $queue); 

echo "Queue is ".F\toString($queue)."\n"; 

Here, we use the append function to perform enqueue, and the head and tail functions for the first item in the queue and dequeuer, respectively. Here is the output of the preceding code:

Queue is [1, 2, 3]
Dequeue-ed item: 1
Queue is [2, 3]
Queue is [2, 3, 4]

Now, we will shift our focus to implementing...