Optional

The goal of the Optional library is to handle elegantly optional parameters in order to avoid control structures like if or switch, and to avoid multiple return types.

The code also becomes more declarative.

Examples

Sending user data to a template

Context: We want to display user data but the phone number is an optional one.

As usually seen

<?php

// ---------------------------------------- interfaces

interface PhoneNumber
{
    public function toString(): string;
}

interface User
{
    public function firstname(): string;
    public function lastname(): string;
    public function phone(): PhoneNumber|null;
}

// ---------------------------------------- implementation

$this->templateEngine->render(
    'template/file/path/',
    [
        'firstname' => $user->firstname(),
        'lastname'  => $user->lastname(),
        'phone'     => is_null($user->phone())
                         ? '--.--.--.--.--'
                         : $user->phone()->toString(),
    ]
);

With Optional

<?php

// ---------------------------------------- interfaces

interface PhoneNumber
{
    public function toString(): string;
}

interface User
{
    public function firstname(): string;
    public function lastname(): string;
    public function phone(): Maybe; // Maybe<PhoneNumber>
}

// ---------------------------------------- implementation

$this->templateEngine->render(
    'template/file/path/',
    [
        'firstname' => $user->firstname(),
        'lastname'  => $user->lastname(),
        'phone'     => $user->phone()
                            ->map(function (PhoneNumber $phone) { return $phone->toString(); })
                            ->getOr('--.--.--.--.--'),
    ]
);