README

Option that takes care of what you unwrap.

Requirements

• PHP 8.1 or higher.

Installation

The package could be installed with composer:

composer require kafkiansky/option

Motivation

Every Option pattern implementation I've seen has allowed you to call unwrap and get either a value or an exception, which, in my opinion, is no different from calling methods from null. Same behaviour. Same error on production. But what if static analysis would make you check for a value before getting it? No problem.

<?php

declare(strict_types=1);

use Kafkiansky\Option\Option;

/**
 * @param Option<non-empty-string> $option
 */
function withName(Option $option): void
{
    echo $option->unwrap();
}

With this code you will get an IfThisIsMismatch error from psalm, because unwrap can only be called on type Some<T>, not None.

Let's fix that:

<?php

declare(strict_types=1);

use Kafkiansky\Option\Option;

/**
 * @param Option<non-empty-string> $option
 */
function withName(Option $option): void
{
    if ($option->isSome()) {
        echo $option->unwrap();
    }
}

Everything is fine now.

This code is also error-prone with NoValue issue:

<?php

declare(strict_types=1);

use Kafkiansky\Option\Option;

/**
 * @param Option<non-empty-string> $option
 */
function withName(Option $option): void
{
    if ($option->isNone()) {
        echo $option->unwrap();
    }
}

But this code has no errors because you have passed a default value for None type, so you can call unwrap without calling isSome.

<?php

declare(strict_types=1);

use Kafkiansky\Option\Option;

/**
 * @param Option<non-empty-string> $option
 */
function withName(Option $option): void
{
    echo $option
        ->map(
            fn (string $name): string => 'User: '. $name,
            fn (): string => 'anonymous',
        )
        ->unwrap()
    ;
}

And this code also contains no errors:

<?php

declare(strict_types=1);

use Kafkiansky\Option\Option;

/**
 * @param Option<non-empty-string> $option
 */
function withName(Option $option): void
{
    echo $option->unwrapOr('anonymous');
}

Limitations

At the moment this package works best with Psalm, because PHPStan does not yet know how to understand the if-this-is annotation.

Testing

$ composer phpunit

License

The MIT License (MIT). See License File for more information.