**FastAPI** is helemaal gebaseerd op deze type hints, ze geven veel voordelen.

Maar zelfs als je **FastAPI** nooit gebruikt, heb je er baat bij om er iets over te leren.

/// note

Als je een Python expert bent en alles al weet over type hints, sla dan dit hoofdstuk over.

///

## Motivatie

Laten we beginnen met een eenvoudig voorbeeld:

```Python
{!../../docs_src/python_types/tutorial001.py!}
```

In veel gevallen is het niet direct duidelijk hoe omgevingsvariabelen nuttig zijn en hoe je ze moet toepassen. Maar ze blijven in veel verschillende scenario's opduiken als je aan het ontwikkelen bent, dus het is goed om er meer over te weten.

* **Geen brainfucks**:
    * Je hoeft geen nieuwe microtaal voor schemadefinities te leren.
    * Als je bekend bent Python types, weet je hoe je Pydantic moet gebruiken.

    // my best guess is that the jdk authors have spent more time optimizing that callpath than this
    // one. (StringCoding$StringDecoder vs. StreamDecoder).  StringCoding has a ton of special cases
    // theoretically we could duplicate all that logic here to try to beat 'new String' or at least
    // come close.
    USING_DECODER_WITH_SIZE_HINT {
      @Override

				if meta, err := xl.AppendTo(metaDataPoolGet()); err == nil {
					if best.reusable {
						metaDataPoolPut(best.metadata)
					}
					best.metadata = meta
					best.cached = xl
				}
			}
			toMerge = toMerge[:0]
		}
		if best.name > last {
			select {
			case <-ctxDone:
				return ctx.Err()
			case out <- *best:
				last = best.name
			}
		} else if serverDebugLog {

   * interned, and so does not prevent these instances from being garbage-collected. This most
   * likely does not perform as well as {@link #newStrongInterner}, but is the best alternative when
   * the memory usage of that implementation is unacceptable.
   */
  @GwtIncompatible("java.lang.ref.WeakReference")
  public static <E> Interner<E> newWeakInterner() {

 * does not participate in any [interceptors][Interceptor] or [event listeners][EventListener]. It
 * doesn't include the motivating request's HTTP headers or even its full URL; only the target
 * server's hostname is sent to the proxy.
 *
 * Prior to sending any CONNECT request OkHttp always calls the proxy authenticator so that it may
 * prepare preemptive authentication. OkHttp will call [authenticate] with a fake `HTTP/1.1 407

   * interned, and so does not prevent these instances from being garbage-collected. This most
   * likely does not perform as well as {@link #newStrongInterner}, but is the best alternative when
   * the memory usage of that implementation is unacceptable.
   */
  @GwtIncompatible("java.lang.ref.WeakReference")
  public static <E> Interner<E> newWeakInterner() {

 *
 * <h2>Prefer <a href="https://github.com/ben-manes/caffeine/wiki">Caffeine</a> over Guava's caching
 * API</h2>
 *
 * <p>The successor to Guava's caching API is <a
 * href="https://github.com/ben-manes/caffeine/wiki">Caffeine</a>. Its API is designed to make it a
 * nearly drop-in replacement. It requires Java 8+, and is not available for Android or GWT/J2CL,
 * and may have <a href="https://github.com/ben-manes/caffeine/wiki/Guava">different (usually

   * <p><b>Warning:</b> a new random seed for these functions is chosen each time the {@code
   * Hashing} class is loaded. <b>Do not use this method</b> if hash codes may escape the current
   * process in any way, for example being sent over RPC, or saved to disk. For a general-purpose,
   * non-cryptographic hash function that will never change behavior, we suggest {@link
   * #murmur3_128}.
   *