The Option type represents a value that might or might not be there. It's all about
null safety in PHP!
Note
Inspired by Rust's Option type and other languages like Scala, Swift, F#, etc.
composer require yceruto/option-typeIn PHP, denoting the absence of a value is done with null, e.g. when a divide
function returns null if the divisor is 0.
function divide(int $dividend, int $divisor): ?int
{
if (0 === $divisor) {
return null;
}
return intdiv($dividend, $divisor);
}
function success(int $result): string {
return sprintf('Result: %d', $result);
}
$result = divide(10, 2);
echo success($result);Can you spot the issue in this code? Apparently, everything is fine until you try to
divide by zero. The function will return null, and the success() function will throw
a TypeError because it expects an int value, not null.
The issue with this approach is that it's too easy to overlook checking if the value is
null, leading to runtime errors, and this is where the Option type comes in handy: it
always forces you to deal with the null case.
Options often work with pattern matching to check if there’s a value and act accordingly,
always making sure to handle the null case.
use Std\Type\Option;
use function Std\Type\Option\none;
use function Std\Type\Option\some;
/**
* @return Option<int>
*/
function divide(int $dividend, int $divisor): Option
{
if (0 === $divisor) {
return none();
}
return some(intdiv($dividend, $divisor));
}
function success(int $result): string {
return sprintf('Result: %d', $result);
}
// The return value of the function is an Option
$result = divide(10, 2);
// Pattern match to retrieve the value
echo $result->match(
// The division was valid
some: fn (int $v) => success($v),
// The division was invalid
none: fn () => 'Division by zero!',
);Tip
You can use the functions some() and none() as quick ways to create an Option
instance. some() is just like new Some(), meaning it includes a value, while
none() is the same as new None(), indicating it is missing a value.
This software is published under the MIT License