Wait! ✋ Is that folding plugin really necessary? 🤔 (Replaceable with Tree-sitter)

This article is a post for Vim Ekiden on 11/7.
The previous article was Tips for Using Registers Effectively by perry.

Added on 2025-11-21:
The purpose of this article is solely to promote Neovim's features.
There is no intention to criticize or slander any specific plugins. Thank you for your understanding.

TL;DR

As long as the parser corresponding to the file is installed, you can enable automatic fold detection by configuring it like this.

Introduction

There are many plugins available for Neovim, some of which replicate IDE-like folding.

• kevinhwang91/nvim-ufo
• chrisgrieser/nvim-origami

Due to the existence of such plugins, some might mistakenly believe that automatic fold detection in Neovim requires dedicated plugins or complex configurations.
However, in reality, for most use cases, this objective can be achieved using only nvim-treesitter.

Example Configuration

Specifically, you can write it as follows:

vim.o.foldexpr = "v:lua.vim.treesitter.foldexpr()"
vim.o.foldlevel = 99
vim.o.foldmethod = "expr"
vim.o.foldtext = "" -- Optional; for those who dislike the default fold display

vim.treesitter.foldexpr()

This is a built-in function of Neovim itself, and the actual Lua module can be referenced here.
In other words, in theory, syntax-based automatic fold detection is possible even without installing nvim-treesitter.
One point to note is that this function returns a value as if no folds exist if the target parser is not installed. Therefore, in the end, it is effectively necessary.

Bonus

This technique is already incorporated into SnaxVim, which I introduced previously.
In a recent update, it now supports the main branch of nvim-treesitter (settings for the master branch are also kept just in case). If you are having trouble with the migration, please take this opportunity to check it out. Your feedback would be greatly appreciated!

🔗 Repository: https://github.com/SnaxVim/SnaxVim