[sophacles]

Various plugins can do it on a per language basis, but tree sitter is a nice abstraction that allows such commands to be done with a simple mapping - then tree sitter (with a per-language plugin) will parse to the same ASTish thing, so any language that has function arguments will have the same commands working the same way.

I'm actually kind of excited about tree-sitter - it's not a neovim feature, it's an independent project that can be used a lot of places. I think the effect will be similar to how LSP changed the landscape from "every editor does some parts of handling language X well, but the parts each editor does are different from each other" to "all the editors get this feature when the language server does", just for syntax highlighting and syntax aware edition.