psalm-plugin/README.md

# PSL Psalm Plugin

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## Installation

Supported installation method is via [composer](https://getcomposer.org):

```shell
composer require php-standard-library/psalm-plugin --dev
```

## Usage

To enable the plugin, add the `Psl\Psalm\Plugin` class to your psalm configuration using `psalm-plugin` binary as follows:

```shell
php vendor/bin/psalm-plugin enable php-standard-library/psalm-plugin
```

## Type improvements

Given the following example:

```php
use Psl\Type;

$specification = Type\shape([
  'name' => Type\string(),
  'age' => Type\int(),
  'location' => Type\optional(Type\shape([
    'city' => Type\string(),
    'state' => Type\string(),
    'country' => Type\string(),
  ]))
]);

$input = $specification->coerce($_GET['user']);

/** @psalm-trace $input */
```

Psalm assumes that `$input` is of type `array<"age"|"location"|"name", array<"city"|"country"|"state", string>|int|string>`.

If we enable the `php-standard-library/psalm-plugin` plugin, you will get a more specific
and correct type of `array{name: string, age: int, location?: array{city: string, state: string, country: string}}`.

## Compatibility

| PSL | Psalm plugin | Psalm |
|-----|------------|-------|
| 2.x | ^2.1       | v5    |
| 2.x | ~2.0.0     | v4    |
| 1.x | 1.x        | v4    |

## Sponsors

Thanks to our sponsors and supporters:

| JetBrains |
|---|
| <a href="https://www.jetbrains.com/?from=PSL ( PHP Standard Library )" title="JetBrains" target="_blank"><img src="https://res.cloudinary.com/azjezz/image/upload/v1599239910/jetbrains_qnyb0o.png" height="120" /></a> |

## License

The MIT License (MIT). Please see [`LICENSE`](./LICENSE) for more information.