Launch JupyterLab with basic LSP support

.flake8

[flake8]
# Match black
max-line-length = 88
# Allow asymmetric commas, etc.
extend-ignore = 
    E203, 
    # Spurious warnings in JupyterLab for code cells that follow Markdown cells
    E303
exclude = .git,__pycache__,build,dist,.venv
max-complexity = 10

README.md

JupyterLab linting example

See overrides.json for user-settings under @jupyter-lsp/jupyterlab-lsp:plugin. This can be installed / linked into <sys-prefix>/share/jupyter/lab/settings

demo.ipynb

{
 "cells": [
  {
   "cell_type": "code",
   "execution_count": 8,
   "id": "4fcc80ee-5931-4d92-8b0a-b93279921ef2",
   "metadata": {},
   "outputs": [],
   "source": [
    "import functools"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "f8f5cbba-80a7-4e84-a649-229cfd6ab29d",
   "metadata": {},
   "source": [
    "## Hover"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "2a3c6d09-8080-478b-a36c-604068cecc33",
   "metadata": {},
   "source": [
    "Hover over any piece of code; if an underline appears, you can press <kbd>Ctrl</kbd> to get a tooltip with function/class signature, module documentation or any other piece of information that the language server provides"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "id": "6001f756-a79c-437e-898e-aef681527f6d",
   "metadata": {},
   "outputs": [],
   "source": [
    "f = functools.partial(print, 1)"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "325faf28-3699-4ec9-b51a-27cd3f5d9741",
   "metadata": {},
   "source": [
    "## Diagnostics\n",
    "See squiggle below."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "id": "e904414e-c7c1-43b3-b110-09a53c36cc0c",
   "metadata": {},
   "outputs": [],
   "source": [
    "import statistics"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "68a45391-e0e6-43b6-9757-cbbcfad7b211",
   "metadata": {},
   "source": [
    "## Continuous hinting\n",
    "Set `continuousHinting: true`"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "085367a1-1a30-42f7-b986-7e1157c7a2b6",
   "metadata": {},
   "outputs": [],
   "source": []
  }
 ],
 "metadata": {
  "kernelspec": {
   "display_name": "Python 3 (ipykernel)",
   "language": "python",
   "name": "python3"
  },
  "language_info": {
   "codemirror_mode": {
    "name": "ipython",
    "version": 3
   },
   "file_extension": ".py",
   "mimetype": "text/x-python",
   "name": "python",
   "nbconvert_exporter": "python",
   "pygments_lexer": "ipython3",
   "version": "3.13.6"
  }
 },
 "nbformat": 4,
 "nbformat_minor": 5
}

overrides.json

{
  "@jupyter-lsp/jupyterlab-lsp:plugin": {
    "language_servers": {
      "pylsp": {
        "priority": 100,
        "serverSettings": {
          "pylsp.plugins.flake8.config": ".flake8",
          "pylsp.plugins.flake8.enabled": true,
          "pylsp.plugins.pycodestyle.enabled": false,
          "pylsp.plugins.pydocstyle.enabled": false,
          "pylsp.plugins.pyflakes.enabled": false,
          "pylsp.plugins.pylint.enabled": false,
          "pylsp.plugins.yapf.enabled": false
        }
      }
    }
  }
}

postBuild

#!/usr/bin/env bash
set -eux

mkdir -p ${NB_PYTHON_PREFIX}/share/jupyter/lab/settings
cp ./overrides.json ${NB_PYTHON_PREFIX}/share/jupyter/lab/settings

requirements.txt

jupyterlab
python-lsp-server[all]
jupyterlab-lsp
# Code formatting
jupyterlab-code-formatter
black
isort