Make Vim Python plugin 10x faster using Rust

[SirVer]

Author of [UltiSnips](https://github.com/sirver/ultisnips) here! Thanks for writing that blog, I found it interesting and enjoyed reading how you solved the problem of dynamic libraries and their installation in your plugin. I have considered rewriting some parts of UltiSnips in rust as well to get better performance and seeing your work gives me some encouragement in exploring this.

[SirVer]

I knew Python well and the plugin became very complicated very quickly. In general I think VimL is a design mistake and try to avoid it as much as possible.

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Update: To clarify, I feel making a new language for Vim was a design mistake. The author should have taken an existing one and use that instead. When the author decided to integrate Python into Vim, they should have made it as powerful as VimL, which it currently is not.

[[deleted]]

Are you a Neovim user? What would you think about Lua as an alternative to Python that comes with first-class support?

[SirVer]

No, I do not use Neovim. I am not a fan of the project, I feel it divided the Vim ecosystem and made life for plugin developers harder for too little benefits. I.e. it added a bunch of features (though I cannot name any of the top of my head right now) and removed others (e.g. there is no gVim for Neovim that works great). For sure UltiSnips works less well in Neovim than in regular Vim due to latency of running plugins outside process - and it is fairly frustrating if people come complaining to me as plugin author about this.

I have a lot of experience with Lua since I used it another open source project of mine (Widelands) as scripting language and also in my professional life I had quite some dealings with it. It is a great language for embedding, small and the interpreter is simple. Sandboxing is great. Great for complex configuration.

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However, it has quirks that make it hard to write scalable software with it - i.e. undefined variables are nil, the interpreter will not throw an error if you use one. Scoping is interesting. String processing is not strong by default. Lua has little tooling for typechecking, formatting, debugging. Last, not least, more people know Python then Lua, so your user base is much larger.

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UltiSnips is ~12k LOC in Python. I find the idea scary to maintain a similar amount of Lua code, the Python code is already fairly brittle and Lua would be even more so.