> PEP 658 went live on PyPI in May 2023. uv launched in February 2024. uv could be fast because the ecosystem finally had the infrastructure to support it. A tool like uv couldn’t have shipped in 2020. The standards weren’t there yet.
In 2020 you could still have a whole bunch of performance wins before the PEP 658 optimization. There's also the "HTTP range requests" optimization which is the next best thing. (and the uv tool itself is really good with "uv run" and "uv python".)
> What uv drops: Virtual environments required. pip lets you install into system Python by default. uv inverts this, refusing to touch system Python without explicit flags. This removes a whole category of permission checks and safety code.
pip also refuses to touch system Python without explicit flags?
For uv, there are flags that allow it, so it doesn't really "removes a whole category of permission checks and safety code"? uv has "permission checks and safety code" to check if it's system python? I don't think uv has "dropped" anything here.
> Optimizations that don’t need Rust: Python-free resolution. pip needs Python running to do anything.
This seems to me to be implying that python is inherently slow, so yes, this optimization requires a faster language? Or maybe I don't get the full point.
> Where Rust actually matters: No interpreter startup. ... uv is a single static binary with no runtime to initialize.
Some issues I noticed were:
> PEP 658 went live on PyPI in May 2023. uv launched in February 2024. uv could be fast because the ecosystem finally had the infrastructure to support it. A tool like uv couldn’t have shipped in 2020. The standards weren’t there yet.
In 2020 you could still have a whole bunch of performance wins before the PEP 658 optimization. There's also the "HTTP range requests" optimization which is the next best thing. (and the uv tool itself is really good with "uv run" and "uv python".)
> What uv drops: Virtual environments required. pip lets you install into system Python by default. uv inverts this, refusing to touch system Python without explicit flags. This removes a whole category of permission checks and safety code.
pip also refuses to touch system Python without explicit flags?
For uv, there are flags that allow it, so it doesn't really "removes a whole category of permission checks and safety code"? uv has "permission checks and safety code" to check if it's system python? I don't think uv has "dropped" anything here.
> Optimizations that don’t need Rust: Python-free resolution. pip needs Python running to do anything.
This seems to me to be implying that python is inherently slow, so yes, this optimization requires a faster language? Or maybe I don't get the full point.
> Where Rust actually matters: No interpreter startup. ... uv is a single static binary with no runtime to initialize.
This one's pretty petty/pedantic, but "Rust technically has a very lightweight runtime." https://users.rust-lang.org/t/does-rust-have-a-runtime/11406...
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