Fail-fast feature

[uriyyo]

Basic implementation here - #1321

Context:
#1322 (comment)
pydantic/pydantic#9708 (comment)

fail-fast feature might be extended and used not only for sequence types. It might be useful for other types like mappings or models.

I can see that it can be powerful feature when you can from python validator stop validation process by raising an exception.
As was mentioned by @adriangb here - #1322 (comment)

I would like to work on both features if you don't mind.

Please let me know if you have some tips and ideas about implementation!

cc @sydney-runkle @adriangb

[sydney-runkle]

@uriyyo,

That sounds wonderful. Thanks for your amazing work here.

I like the idea of:

1. A runtime flag fail_fast that is passed to model_validate
2. A FailNow data structure that can be used in custom validators
3. Generally, support for failing early / fast for lots of data types.

Let's confirm with @davidhewitt and @adriangb before moving forwards :).

[davidhewitt]

Seems fine to me. I'm less sure about the FailNow structure; it might be better to instead pass fail_fast in the info and then let custom validators decide when to fail fast that way.