untangled_snakes is a python library and command-line utility to resolve a set of python requirements such as requests[dev] into a JSON object, representing the dependency tree as well as a list of sdists, wheels and their hashes. Built on resolvelib and packaging.
As of time of writing, it resolves basic packages and can print a lock-file compatible with dream2nix's fetchPipMetadata, but does not yet handle platform compatibility markers correctly and only supports locking for the platform it runs on.
The main reason to write this is that pip doesn't provide an API. But in order to automatically build python packages in dream2nix, we need to have a full picture of the dependency tree before we start building.
pip recently introduced an optional installation report which we currently use in dream2nix's fetchPipMetadata to do the locking.
While we also need to evaluate extras & platform compatibility there ourselves it works well as long as we stay on one platform.
But we did not manage to get cross-platform locking, i.e. generating a lock file for x86_64-linux on a aarch64-darwin machine with this approach.
Still too early to tell whether this experiment will be successful and/or easier than hacking cross-platform dry-run installs
into pip in the end. And - as stated above - not ready for general usage yet.