[AstroJetson]

> uv is an extremely fast Python package and project manager, written in Rust.

Is there a version of uv written in Python? It's weird (to me) to have an entire ecosystem for a language and a highly recommended tool to make your system work is written in another language.

[sgeisenh]

Similar to ruff, uv mostly gathers ideas from other tools (with strong opinions and a handful of thoughtful additions and adjustments) and implements them in Rust for speed improvements.

Interestingly, the speed is the main differentiator from existing package and project management tools. Even if you are using it as a drop-in replacement for pip, it is just so much faster.

[zahlman]

They are not making a Python version.

There are many competing tools in the space, depending on how you define the project requirements.

Contrary to the implication of other replies, the lion's share of uv's speed advantage over Pip does not come from being written in Rust, from any of the evidence available to me. It comes from:

* bootstrapping Pip into the new environment, if you make a new environment and don't know that you don't actually have to bootstrap Pip into that environment (see https://zahlman.github.io/posts/2025/01/07/python-packaging-... for some hints; my upcoming post will be more direct about it - unfortunately I've been putting it off...)

* being designed up front to install cross-environment (if you want to do this with Pip, you'll eventually and with much frustration get a subtly broken installation using the old techniques; since 22.3 you can just use the `--python` flag, but this limits you to environments where the current Pip can run, and re-launches a new Pip process taking perhaps an additional 200ms - but this is still much better than bootstrapping another copy of Pip!)

* using heuristics when solving for dependencies (Pip's backtracking resolver is exhaustive, and proceeds quite stubbornly in order)

* having a smarter caching strategy (it stores uncompressed wheels in its cache and does most of the "installation" by hard-linking these into the new environment; Pip goes through a proxy that uses some opaque cache files to simulate re-doing the download, then unpacks the wheel again)

* not speculatively pre-loading a bunch of its own code that's unlikely to execute (Pip has large complex dependencies, like https://pypi.org/project/rich/, which it vendors without tree-shaking and ultimately imports almost all of, despite using only a tiny portion)

* having faster default behaviours; e.g. uv defaults to not pre-compiling installed packages to .pyc files (since Python will do this on the first import anyway) while Pip defaults to doing so

* not (necessarily) being weighed down by support for legacy behaviours (packaging worked radically differently when Pip first became publicly available)

* just generally being better architected

None of these changes require a change in programming language. (For example, if you use Python to make a hard link, you just use the standard library, which will then use code written in C to make a system call that was most likely also written in C.) Which is why I'm making https://github.com/zahlman/paper .

[jaapz]

But also, because it's written in rust. There are tools written in python that do these smart caching and resolving tricks as well, and they are still orders of magnitude slower

[zahlman]

Such as?

Poetry doesn't do this caching trick. It creates its own cache with the same sort of structure as Pip's, and as far as I can tell it uses its own reimplementation of Pip's core installation logic from there (including `installer`, which is a factored-out package for the part of Pip that actually unpacks the wheel and copies files).

[ebb_earl_co]

Well, I use Debian and Bash: pretty much everything to make my system work, including and especially Python development, is written in C, another language!

[pjc50]

uv wins precisely because it isn't written in python. As various people have pointed out, it can complete its run before competing python implementations have finished handling their imports.

Besides, the most important tool for making python work, the python executable itself, is written in C. People occasionally forget it's not a self-hosting language.

[dralley]

pip?

A tool written in Python is never going to be as fast as one written in Rust. There are plenty of Python alternatives and you're free to use them.