strict-paredit.nvim

A strict paredit-like plugin for Neovim that uses treesitter to prevent unbalanced delimiters in Lisp-like languages. Inspired by Emacs' smartparens-strict-mode.

Features

• Strict insertion: Opening delimiters auto-pair; closing delimiters only move over existing ones (never create unmatched)
• Paired deletion: Deleting any delimiter automatically deletes its match
• Treesitter-powered: Uses treesitter for accurate delimiter matching
• String/comment aware: Strict mode is bypassed inside strings and comments
• Multiple modes: Works in both insert and normal mode

Installation

Using lazy.nvim / LazyVim

Add to your plugins (e.g., ~/.config/nvim/lua/plugins/strict-paredit.lua):

return {
  "sundbp/strict-paredit.nvim",  -- or local path, see below
  dependencies = {
    "nvim-treesitter/nvim-treesitter",
  },
  ft = { "clojure", "fennel", "scheme", "lisp", "racket", "janet", "hy", "query" },
  opts = {
    -- your options here (see Configuration below)
  },
}

Local development / before publishing to GitHub

return {
  dir = "~/projects/strict-paredit.nvim",  -- path to your local clone
  dependencies = {
    "nvim-treesitter/nvim-treesitter",
  },
  ft = { "clojure", "fennel", "scheme", "lisp", "racket" },
  opts = {},
}

Using packer.nvim

use {
  "yourusername/strict-paredit.nvim",
  requires = { "nvim-treesitter/nvim-treesitter" },
  config = function()
    require("strict-paredit").setup()
  end
}

Configuration

require("strict-paredit").setup({
  -- Filetypes to enable strict paredit (defaults shown)
  filetypes = {
    "clojure",
    "fennel",
    "scheme", 
    "lisp",
    "racket",
    "janet",
    "hy",
    "lfe",
    "query",
  },
  
  -- Show notification warnings when operations are blocked (default: true)
  notify = true,
})

Behavior

Insert Mode

Key	Behavior
(, [, {	Inserts both opening and closing delimiter, cursor between
), ], }	If at matching closer, moves over it; otherwise blocked
<BS>	If before delimiter, deletes both it and its match
<Del>	If on delimiter, deletes both it and its match

It also handles strings like "string" by inserting matching "-characters and always deleting them as a pair. If you type a " in this position "foo |bar", then an escaped " will be inserted.

Normal Mode

Key	Behavior
x	If on delimiter, deletes both it and its match
X	If before delimiter, deletes both it and its match
s	Blocked on delimiters (would unbalance)

Examples

;; Typing '(' produces:
(|)  ;; cursor at |

;; With cursor here: (foo bar|)
;; Typing ')' moves cursor: (foo bar)|

;; With cursor here: (|foo bar)
;; Pressing backspace deletes both parens: |foo bar

;; With cursor on opening paren: |(foo bar)
;; Pressing 'x' in normal mode: |foo bar

Escape Hatches

When you genuinely need to bypass strict mode:

:StrictPareditForceDelete   " Force delete char under cursor
:StrictPareditForceBackspace " Force delete char before cursor

API

local sp = require("strict-paredit")

-- Enable for current buffer (useful for unlisted filetypes)
sp.enable()

-- Check if deletion would be allowed at cursor
sp.can_delete_at_cursor()  -- returns boolean

Requirements

• Neovim 0.9+ (for treesitter APIs)
• Treesitter parser installed for your language (:TSInstall clojure, etc.)

Limitations

1. Treesitter dependent: If treesitter can't parse the buffer (e.g., during heavy editing with syntax errors), matching may fail. The plugin will block operations it can't verify as safe.

2. No slurp/barf: This plugin focuses on strict delimiter handling. For structural editing operations like slurp, barf, raise, etc., use nvim-paredit alongside this plugin.

3. Reader macros: Some Lisp reader macros (#(, @, etc.) may not be handled perfectly depending on the treesitter grammar.

Complementary Plugins

This plugin pairs well with:

• nvim-paredit - Structural editing (slurp, barf, etc.)
• nvim-treesitter - Required for treesitter support
• conjure - Interactive evaluation for Lisps

License

MIT