Add AnthropicGenerator

[mathislucka]

Is your feature request related to a problem? Please describe.
Anthropic models are widely used. We should support them in 2.0.

Describe the solution you'd like
Generator similar to the Anthropic support in 1.x

Tasks

Beta Give feedback

1. The code is documented with docstrings and was merged in the main branch
2. Docs are published at https://docs.haystack.deepset.ai/
3. There is a Github workflow running the tests for the integration nightly and at every PR
4. A label named like integration:<your integration name> has been added to this repo
5. The labeler.yml file has been updated
6. The package has been released on PyPI
7. An integration tile has been added to https://github.com/deepset-ai/haystack-integrations
8. The integration has been listed in the Inventory section of this repo README
9. There is an example available to demonstrate the feature
10. The feature was announced through social media

[sahusiddharth]

@mathislucka can you provide me with some kind of starting point, about the minimal interface that is required for this?

[anakin87]

@sahusiddharth I can have a look later today and point to the right resources/examples.

It is necessary that you have access to Anthropic to do local experiments. Do you have access to Anthropic?

[sahusiddharth]

Hi @anakin87, currently I don't have access. Would you mind sharing an API key for experimentation in the meantime? Thanks!

[anakin87]

Anthropic is only available for some countries, so I can't share with you a usable API key.
I would advise you to focus on some other contribution. 💟

[vblagoje]

The issue was a bit prematurely closed. The only two remaining tasks (as of 18.3.24) are publishing the docs and social media announcement