Add --pypi to pixi add subcommand

[ruben-arts]

We want the users to have the ability to add pypi-dependencies to the pixi.toml.

pixi add --pypi haystack[inference]
# Result: haystack = { version = "==x.y.z", extra = ["inference"] }
pixi add --pypi "pytest==7.4.1"
# Result: pytest = "==7.4.1"
pixi add --pypi numpy
# Result: numpy = "==x.y.z"

[rahuldave]

For nice UX, do we want add to follow on to pypi if no matches found in conda-forge or similar? For example, for haystack. Or be explicit? (currently i believe we have to explicitly add to pypi-dependencies in pixi.toml...

Regardless this issue i think is critical for adoption and user-friendly usage!

[ruben-arts]

I think you are right that that would be very helpful, but first lets go the explicit route and then see how we can make it more user friendly. Especially while the PyPI integration is in alpha mode.

[codegod100]

@rahuldave I came here to say the same thing. I'm kinda lazy and just wanna "pixi add" without config stuff. @ruben-arts might have a good point on wanting the dust to settle first.

[rahuldave]

I think "pixi add -pypi" is a great start! I am a bit confused about resolution though. Dependencies for a pypi install are pypi satisfied or fail , or will the resolution go back to conda channels?