# AMPHP v2 → v3 Migration

**Do NOT follow any v2 patterns.** If you see them in existing code, rewrite them.

| v2 (old, WRONG) | v3 (current, correct) |
|---|---|
| `Amp\Loop::run()` | `Revolt\EventLoop::run()` |
| `yield $promise` | `$future->await()` or `async(fn() => ...)` |
| `Promise` interface | `Future` class |
| `Coroutine`, generators | PHP Fibers, `async()` |
| `Amp\call(fn() { yield ... })` | `async(fn() { ... })` |
| `Deferred->resolve()` | `DeferredFuture->complete()` |
| `Deferred->reject()` | `DeferredFuture->error()` |
| `$amp->asyncCall()`, `asyncCoroutine()` | `async()` |
| `Amp\Promise\wait()` | `$future->await()` inside fiber or `EventLoop::run(fn() => ...)` |
| `Amp\Iterator` | `Amp\Pipeline\Queue` / `Pipeline::fromIterable()` |
| `Amp\Emitter` | `Amp\Pipeline\Queue` |
| `Amp\Loop::defer()` | `Revolt\EventLoop::defer()` |
| `Amp\Loop::delay()` | `Revolt\EventLoop::delay()` |
| `$promise->onResolve(fn($err, $val) => ...)` | `$future->map(fn($val) => ...)->catch(fn($e) => ...)` |

## v3 Minimum Requirements

```json
{
    "require": {
        "php": ">=8.1",
        "revolt/event-loop": "^1",
        "amphp/amp": "^3"
    }
}
```

## How Fibers Replace Generators

```php
// v2: generator-based coroutine (WRONG)
function fetchData(string $url): \Amp\Promise {
    return Amp\call(function () use ($url) {
        $response = yield $httpClient->request($url);
        return yield $response->getBody()->buffer();
    });
}

// v3: PHP Fiber (correct)
function fetchData(string $url): string {
    $response = $httpClient->request(new Request($url));
    return $response->getBody()->buffer(); // suspends fiber, not the whole thread
}
```