Type.md

Typhoon Type

Typhoon Type is an abstraction for the PHP static type system, inspired by two popular analyzers Psalm and PHPStan.

Once full and stable, Typhoon Type might be proposed as a PSR or PER.

Installation

composer require typhoon/type

Constructing types

Types can be constructed via the types static factory.

use Typhoon\Type\types;

/**
 * Equivalent of array{
 *     a: non-empty-list,
 *     b?: int|float,
 *     c: Traversable<numeric-string, false>,
 *     d: callable(PDO::*, TSend:Generator=, scalar...): void,
 *     ...
 * }
 */
$type = types::arrayShape([
    'a' => types::nonEmptyString,
    'b' => types::arrayElement(types::union(types::int, types::float), optional: true),
    'c' => types::object(Traversable::class, types::numericString, types::false),
    'd' => types::callable(
        parameters: [
            types::classConstant(types::object(PDO::class), '*'),
            types::param(types::template('TSend', types::atClass(Generator::class)), hasDefault: true),
            types::param(types::scalar, variadic: true),
        ],
        return: types::void,
    ),
], sealed: false);

Note that all classes that implement Type (except types:: itself) are @internal and should not be used outside the library.

Analyzing types

Typhoon types should be analyzed only via TypeVisitors: $type->accept(new MyVisitor()). Comparison operators and instanceof should never be used with Typhoon types for two reasons:

1. type classes are internal and not subject to backward compatibility,
2. equal types might have different internal structure (e.g., one is decorated).

Comparing types

Typhoon team is currently working on a type comparator. Until it is released, you can use DefaultTypeVisitor for simple checks:

use Typhoon\Type\Type;
use Typhoon\Type\DefaultTypeVisitor;

$isMixed = $type->accept(
    new /** @extends DefaultTypeVisitor<bool> */ class () extends DefaultTypeVisitor {
        protected function default(Type $self): mixed
        {
            return false;
        }

        public function mixed(Type $self): mixed
        {
            return true;
        }
    },
);