examples.md

Option type examples

This section provides examples of how to use the Option type in your PHP code.

Example 1: Handling the presence or absence of a value in return types

Let's say you have a function that retrieves a user from a database by its ID. The function can return null if the user is not found. Instead of returning null, you can use the Option type to explicitly handle the presence or absence of the user.

use App\Model\User;
use Std\Type\OptionFactory;

/**
 * @return Option<User>
 */
function findUser(int $id): Option
{
    $user = // get user from database by $id ... it can return null

    return OptionFactory::from($user); // None if null, otherwise Some($user)
}

$user = findUser(1)->expect('A user must exist!'); // throws LogicOptionException if it does not exist
// do something safely with $user instance...

// map the user found to a DTO or create a new one if not found
$dto = findUser(1)->mapOr(UserDto::from(...), UserDto::new());
// do something safely with $dto instance...

Example 2: Handling the presence or absence of a value in a function argument

You can also use the Option type to handle the presence or absence of a value in a function argument.

use Std\Type\Option;
use function Std\Type\Option\none;
use function Std\Type\Option\some;

/**
 * @param Option<User> $user
 */
function greet(Option $user): string
{
    return $user->match(
        some: fn (User $u) => "Hello, {$u->name()}!",
        none: fn () => 'Hello, World!',
    );
}

$user = new User(name: 'Alice');

echo greet(some($user)); // Outputs: Hello, Alice!
echo greet(none()); // Outputs: Hello, World!