sextant.nvim

Common Lisp development environment for Neovim — LSP + interactive debugger powered by Sextant.

Features

• LSP: completions, go-to-definition, find references, hover, document symbols, semantic tokens, diagnostics
• REPL: evaluate expressions in a live SBCL image from the debug console
• Debugger: condition/restart system mapped to DAP — stack frames, variable inspection, restart invocation
• Single process: LSP and DAP run simultaneously in the same SBCL image, sharing full introspection

Prerequisites

Sextant requires SBCL and Quicklisp to build from source.

Install SBCL

# Debian/Ubuntu
sudo apt install sbcl

# macOS
brew install sbcl

# Arch
sudo pacman -S sbcl

Install Quicklisp

curl -O https://beta.quicklisp.org/quicklisp.lisp
sbcl --load quicklisp.lisp --eval '(quicklisp-quickdist:install :path "~/quicklisp/")' --eval '(ql:add-to-init-file)' --quit

Build Sextant

git clone https://github.com/parenworks/sextant.git
cd sextant
make build

This produces a sextant binary. Either add it to your PATH or pass the path in the plugin config.

Installation

Using lazy.nvim:

{
  "parenworks/sextant.nvim",
  dependencies = {
    "neovim/nvim-lspconfig",
    "mfussenegger/nvim-dap",       -- optional, for debugger/REPL
    "rcarriga/nvim-dap-ui",        -- optional, for debugger UI
    "nvim-neotest/nvim-nio",       -- required by nvim-dap-ui
  },
  ft = "lisp",
  opts = {},
}

Configuration

require("sextant").setup({
  -- Path to sextant binary (auto-detected if on PATH)
  cmd = nil,

  -- DAP server port (sextant listens on this for debugger connections)
  dap_port = 6009,

  -- Filetypes to activate on
  filetypes = { "lisp" },

  -- Root patterns for project detection
  root_patterns = { ".git", "*.asd", "*.asdf" },
})

Usage

LSP

Open any .lisp file — LSP starts automatically.

• gd — go to definition
• gr — find references
• K — hover documentation
• <leader>ss — document symbols

Debugger / REPL

Command	Keymap	Description
:SextantAttach	<leader>dc	Attach debugger to live SBCL image
:SextantLaunch		Launch current file in debugger
:SextantRepl		Toggle REPL console
:SextantDisconnect	<leader>dx	Disconnect debugger

Debug Keymaps

Keymap	Description
<leader>db	Toggle breakpoint
<leader>dc	Continue / Start debug session
<leader>di	Step into
<leader>do	Step over
<leader>dO	Step out
<leader>dr	Run to cursor
<leader>ds	Restart session
<leader>de	Eval expression under cursor
<leader>du	Toggle DAP UI

REPL Commands

In the debug console (:SextantRepl or :DapToggleRepl):

;; Evaluate any Common Lisp expression
(+ 1 2)
(defun greet (name) (format nil "Hello, ~a!" name))
(greet "world")

;; Load a file into the live image
(load "myproject.lisp")

;; When stopped on an error:
:restarts          ;; show available restarts
:restart 0         ;; invoke restart by index

How It Works

Sextant runs as a single SBCL process:

• LSP communicates over stdio (standard Neovim LSP transport)
• DAP listens on a TCP socket (default port 6009)

Both share the same Lisp image, so definitions loaded via the REPL are immediately available to LSP features like go-to-definition and completions.

When a condition (error) is signaled, Sextant's debugger hook intercepts it and sends a DAP stopped event. The DAP UI shows the stack trace, local variables, and available restarts — the full Common Lisp condition/restart system exposed through your editor.

License

MIT