Support PEP 751 - Pylock

[leonballoni]

Hello! I noticed a new release of PEP at https://peps.python.org/pep-0751/ Python Peps and would be very interesting to see this standard implemented in Poetry. Is it something possible in the future?

[radoering]

Short answer: Yes, but it may take a while.

Long answer:

There are two ways of supporting PEP 751:

1. as export format in poetry-plugin-export
2. by replacing poetry.lock

The two ways are not "either or". It makes sense to support both. We will try both although it could turn out to be impracticable to replace poetry.lock if we face any missing features in the PEP. (At the moment, I do not see any blockers, but we can only be sure after having tried to implement it.)

Exporting a pylock.toml will obviously be easier than replacing our lock file. Thus, it might make sense to do this first. On the other hand, exporting a pylock.toml will be trivial if we had already replaced our lock file - it will just be resolving some markers and removing some entries.

Actually, we have already started working towards PEP 751 before it was even accepted. #9427, which has been introduced in Poetry 2.0, is a mandatory precondition for replacing poetry.lock with pylock.toml. Notice that installer.re-resolve is still true per default. (It has to be false in order to replace poetry.lock with pylock.toml.) Most of the fixes regarding markers and dependency resolution in subsequent Poetry releases are related to #9427 so that I think it is slowly becoming stable - which is a precondition for replacing poetry.lock.

Moreover, there are some other PEPs (PEP 735, PEP 639) that we still have to implement and that may have higher priority than PEP 751.

[th0ger]

You may want to ready the similar discussion on uv.
astral-sh/uv#12584

[groodt]

Adding link to this issue #10356