cxMathPreview.nvim

Render LaTeX math written inside code comments as Unicode/ASCII art, inline.

It is inspired by nabla.nvim and reuses its math engine, but fixes the one thing that makes nabla annoying while writing code:

nabla parses the whole buffer as LaTeX, so every $ that legitimately appears in your code (shell variables $HOME, JS template literals ${x}, regex, PHP/Perl, …) gets rendered as a math formula.

cxMathPreview only renders $ ... $ that lives inside a comment. The real code is never touched.

// energy-mass equivalence: $E = mc^2$   <-  rendered inline as  E = mc²
int price = 5;                            //  $price stays $price, it's code

How it works

1. Find comment regions of the visible lines (treesitter @comment nodes when a parser is available, falling back to Vim's built-in syntax highlighting — so it works out of the box without any treesitter parsers).
2. Inside those comment regions only, scan for inline math $ ... $ (and display math $$ ... $$). \$ is treated as a literal dollar, not math.
3. Convert each math snippet with the vendored nabla engine (latex.lua parser → ascii.lua renderer) into Unicode/ASCII art.
4. Show the art inline — the raw $...$ is concealed and replaced by the rendered formula (like nabla).

Requirements

• Neovim 0.9+ (uses vim.treesitter, extmarks, virtual text).
• For best comment detection: a treesitter parser for your filetype (:TSInstall <lang>). Not required — the syntax fallback works for almost every filetype out of the box.
• conceallevel >= 2 is set automatically while enabled (and restored on disable). Your terminal/font must have glyphs like ∑ ∫ √ ² ³ ≈ ≤ α β. A Nerd Font is not required.

Installation

lazy.nvim

Since the repo ends in .nvim, lazy.nvim derives main = "cxMathPreview" automatically, so you can use the opts shorthand:

{
  "cxwx/cxMathPreview.nvim",
  opts = {
    -- see options below
  },
  -- Optional: lazy-load on the commands / a key
  -- cmd = { "CxMathEnable", "CxMathToggle", "CxMathPopup" },
  -- keys = { { "<leader>m", "<cmd>CxMathPopup<cr>" } },
}

Or with an explicit config:

{
  "your-name/cxMathPreview.nvim",
  config = function()
    require("cxMathPreview").setup({
      -- see options below
    })
  end,
}

packer.nvim

use {
  "your-name/cxMathPreview.nvim",
  config = function() require("cxMathPreview").setup() end
}

Usage

Commands (available immediately):

Command	Description
:CxMathToggle	Toggle inline rendering for the current buffer
:CxMathPopup	Show the $...$ formula under the cursor in a float

The Lua API also exposes enable() / disable() / is_enabled() if you want finer control.

Recommended keymap:

vim.keymap.set("n", "<leader>m", function() require("cxMathPreview").popup() end,
  { desc = "Math popup" })
vim.keymap.set("n", "<leader>M", function() require("cxMathPreview").toggle() end,
  { desc = "Toggle inline math" })

Options

There is essentially one option — the highlight group used for rendered math. Everything else (inline conceal, multi-line alignment, concealcursor) is hardcoded. You can skip setup() entirely.

require("cxMathPreview").setup({ hl = "SpecialChar" }) -- default

Examples

A Python file with:

# likelihood: $\mathcal{L}(\theta) = \prod_{i=1}^{n} p(x_i \mid \theta)$
# fraction:   $\frac{1}{1 + e^{-x}}$

renders (inline) roughly as:

# likelihood:  n
#             ─┬─┬─
#              ‖   p(xᵢ ∣ θ)
#             i = 1
# fraction:    1
#             ───────
#              -x
#             1 + e

API

local cx = require("cxMathPreview")
cx.setup(opts)        -- configure + optional auto-enable by filetype
cx.enable(buf?)       -- enable for buffer (default current)
cx.disable(buf?)
cx.toggle(buf?)
cx.is_enabled(buf?)
cx.popup()            -- floating preview of the formula under cursor
cx.render(buf?)       -- force a re-render (rarely needed; auto-refreshes)

Credits

The LaTeX parser (lua/cxMathPreview/latex.lua) and ASCII renderer (lua/cxMathPreview/ascii.lua) are vendored unchanged from nabla.nvim by jbyuki (MIT License, Copyright (c) 2020 jbyuki). The comment-aware layer on top is original.

License

MIT.