Initial proof-of-concept.

.gitignore

+lib/*
+node_modules/*
+tsconfig.tsbuildinfo
+yarn.lock

README.md

+# Finesse Syntax for JupyterLab

package.json

+{
+  "name": "finesse-syntax-jupyterlab",
+  "version": "0.1.0",
+  "description": "Syntax highlighting for kat script within jupyterlab.",
+  "keywords": [
+    "jupyter",
+    "jupyterlab",
+    "jupyterlab-extension"
+  ],
+  "homepage": "https://github.com/my_name/myextension",
+  "bugs": {
+    "url": "https://github.com/my_name/myextension/issues"
+  },
+  "license": "BSD-3-Clause",
+  "author": "Phil Jones",
+  "files": [
+    "lib/**/*.{d.ts,eot,gif,html,jpg,js,js.map,json,png,svg,woff2,ttf}",
+    "style/**/*.{css,eot,gif,html,jpg,json,png,svg,woff2,ttf}"
+  ],
+  "main": "lib/index.js",
+  "types": "lib/index.d.ts",
+  "style": "style/index.css",
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/my_name/myextension.git"
+  },
+  "scripts": {
+    "build": "tsc",
+    "clean": "rimraf lib tsconfig.tsbuildinfo",
+    "prepare": "jlpm run clean && jlpm run build",
+    "watch": "tsc -w"
+  },
+  "dependencies": {
+    "@jupyterlab/application": "^1.2.1",
+    "@jupyterlab/apputils": "^1.2.1",
+    "@jupyterlab/docregistry": "^1.2.1",
+    "@jupyterlab/notebook": "^1.2.2",
+    "@phosphor/disposable": "^1.3.1",
+    "@phosphor/widgets": "^1.9.3",
+    "@types/codemirror": "0.0.82",
+    "codemirror": "5.47.0"
+  },
+  "devDependencies": {
+    "rimraf": "^2.6.1",
+    "typescript": "~3.5.2"
+  },
+  "sideEffects": [
+    "style/*.css"
+  ],
+  "jupyterlab": {
+    "extension": true
+  }
+}

src/codemirror-finesse.ts

+import {
+	Mode
+} from '@jupyterlab/codemirror'
+
+import CodeMirror from 'codemirror';
+
+import 'codemirror/mode/python/python';
+import 'codemirror/addon/mode/multiplex';
+
+declare module 'codemirror' {
+	function multiplexingMode(x: CodeMirror.Mode<any>, ...others: object[]): CodeMirror.Mode<any>;
+	var modeInfo: any[];
+}	
+
+CodeMirror.defineMode("finesse", (config) => {
+	let pmode = CodeMirror.getMode(config, "python");
+	return CodeMirror.multiplexingMode(
+		pmode,
+		{
+			open: '#katcode',
+			close: '"""',
+			mode: CodeMirror.getMode(config, "text/html"),
+			delimStyleOpen: "delimit",
+			delimStyleClose: "string"
+		}
+	)
+});
+
+Mode.getModeInfo().push({
+	name: 'Finesse',
+	mime: "text/python",
+	mode: 'finesse',
+	ext: [],
+});

src/index.ts

+import {
+	IDisposable, DisposableDelegate
+} from '@phosphor/disposable';
+
+import {
+	JupyterFrontEnd, JupyterFrontEndPlugin
+} from '@jupyterlab/application';
+
+import {
+	ToolbarButton
+} from '@jupyterlab/apputils';
+
+import {
+	DocumentRegistry
+} from '@jupyterlab/docregistry';
+
+import {
+	NotebookPanel, INotebookModel
+} from '@jupyterlab/notebook';
+
+import {
+	Mode, CodeMirrorEditor
+} from '@jupyterlab/codemirror'
+
+
+import './codemirror-finesse';
+
+/**
+ * The plugin registration information.
+ */
+const plugin: JupyterFrontEndPlugin<void> = {
+	activate,
+	id: 'my-extension-name:buttonPlugin',
+	autoStart: true
+};
+
+
+/**
+ * A notebook widget extension that adds a button to the toolbar.
+ */
+export
+class ButtonExtension implements DocumentRegistry.IWidgetExtension<NotebookPanel, INotebookModel> {
+	/**
+	 * Create a new extension object.
+	 */
+	createNew(panel: NotebookPanel, context: DocumentRegistry.IContext<INotebookModel>): IDisposable {
+		let callback = () => {
+			console.log(Mode.getModeInfo());
+			panel.content.widgets.forEach(cell => {
+				(cell.editor as CodeMirrorEditor).setOption("mode", "finesse");
+			});
+			//NotebookActions.runAll(panel.content, context.session);
+		};
+		let button = new ToolbarButton({
+			className: 'myButton',
+			iconClassName: 'fa fa-fast-forward',
+			onClick: callback,
+			tooltip: 'Run All'
+		});
+
+		panel.toolbar.insertItem(0, 'runAll', button);
+		return new DisposableDelegate(() => {
+			button.dispose();
+		});
+	}
+}
+
+/**
+ * Activate the extension.
+ */
+function activate(app: JupyterFrontEnd) {
+	app.docRegistry.addWidgetExtension('Notebook', new ButtonExtension());
+};
+
+
+/**
+ * Export the plugin as default.
+ */
+export default plugin;

tsconfig.json

+{
+  "compilerOptions": {
+    "allowSyntheticDefaultImports": true,
+    "composite": true,
+    "declaration": true,
+    "esModuleInterop": true,
+    "incremental": true,
+    "jsx": "react",
+    "module": "esnext",
+    "moduleResolution": "node",
+    "noEmitOnError": true,
+    "noImplicitAny": true,
+    "noUnusedLocals": true,
+    "preserveWatchOutput": true,
+    "resolveJsonModule": true,
+    "outDir": "lib",
+    "rootDir": "src",
+    "strict": true,
+    "strictNullChecks": false,
+    "target": "es2017",
+    "types": []
+  },
+  "include": ["src/*"]
+}