[Type] Introduce the Type API

[azjezz]

closes #42

<?php

require_once __DIR__ . '/../vendor/autoload.php';

use Psl\Type;
use Psl\Collection;

/** @psalm-var Type<iterable<array<int, array<int|string, string>>, Collection\ICollection&Collection\IIndexAccess> $spec */
$spec = Type\iterable(
    Type\arr(Type\int(), Type\arr(Type\array_key(), Type\string())),
    Type\intersection(
        Type\instance_of(Collection\ICollection::class),
        Type\instance_of(Collection\IIndexAccess::class)
    )
);

/**
 * @var null|iterable<array<int, array<int|string, string>>, Collection\ICollection&Collection\IIndexAccess> $value
 */
$value = Type\nullable($spec)->assert(null);

$value = Type\nullable($spec)->assert((static function () {
    yield [4 => ['bar' => 'baz', 1337 => 'qux']] => new Collection\Map([]);
})());

$value = $spec->assert((static function () {
    yield [4 => ['bar' => 'baz', 1337 => 'qux']] => new Collection\Map([]);
})());

try {
    $value = $spec->assert((static function () {
        yield [4 => ['bar' => 'baz', 1337 => 13]] => new Collection\Vector([]);
    })());
} catch (Type\Exception\TypeAssertException $e) {
    //    Expected "string", got "integer".
    print $e->getMessage();
}

try {
    $value = $spec->assert((static function () {
        yield [4 => ['bar' => 'baz', 1337 => 'f']] => new stdClass();
    })());
} catch (Type\Exception\TypeAssertException $e) {
    //    Expected "Psl\Collection\ICollection&Psl\Collection\IIndexAccess", got "stdClass".
    print $e->getMessage();
}

// iterable<array<int, array<array-key, string>>, Psl\Collection\ICollection&Psl\Collection\IIndexAccess>
print $spec->toString();

[psalm-shepherd]

Psalm didn’t find any errors!

[psalm-shepherd]

Psalm didn’t find any errors!

[psalm-shepherd]

Psalm didn’t find any errors!

[psalm-shepherd]

Psalm didn’t find any errors!

[psalm-shepherd]

Psalm didn’t find any errors!

[psalm-shepherd]

Psalm didn’t find any errors!

[psalm-shepherd]

Psalm didn’t find any errors!

[azjezz]

TypeSpec -> Type

[azjezz]

few other things need to be fixed i guess

[psalm-shepherd]

Psalm didn’t find any errors!

[psalm-shepherd]

Psalm didn’t find any errors!