Is there any library for refined types in php?

Question

Is there any library for refined types in php that can allow me to do something like this?

function getAge(int positive $age){
...
}

getAge(-1) // error -1 < 0

Thanks!

Answer 1

You would need to implement Refinement-Types at the engine level. No one did this yet.

Or use a userland Preprocessor, like http://github.com/marcioAlmada/yay.

Or implement the refined types as Value Objects, e.g.

class PositiveInteger 
{
    private $value;

    public static function assertValid(int $value) {
        if ($value < 0) {
            throw new InvalidArgumentException("Not positive");
        }
    }

    public function __construct(int $value) 
    {
        static::assertValid($value);
        $this->value = $value;
    }

    public function getValue(): int 
    {
        return $this->value;
    }

    public function __toString(): string 
    {
        return (string) $this->value;
    }
}

However, this means the int is no longer a scalar and cannot be used in the same way as you'd use a scalar, e.g. all operations would need to be methods. You won't be able to do $age++ anymore.