uv

Why it matters

Python packaging was a running joke for a decade — slow resolvers, conflicting tools, README files that began with "first, install pyenv, then…". uv ended the joke by doing the unglamorous thing: reimplementing the whole stack in Rust with a global module cache and a proper resolver, then making the fast path the default path.

Engineering notes

• One binary, one cache. Downloads are cached globally and hardlinked into environments, so creating a virtualenv is nearly free.
• Compatible, not clever. Speaks the same standards (PEP 508, PEP 517, pyproject.toml) as the tools it replaces — migration is a flag flip, not a rewrite.
• Workspace support done right. Cargo-style workspaces for monorepos, with lockfiles that are actually deterministic.

Limitations

• The ecosystem moves fast; some edge-case workflows (exotic index configurations, legacy setup.py flows) still send you back to pip.
• Windows support lagged Unix initially — mostly caught up now, but worth verifying for your setup.