Updated algorithm.ts

import {
  JupyterFrontEnd,
  JupyterFrontEndPlugin,
} from '@jupyterlab/application';

import {
  IEditorLanguageRegistry,
  IEditorThemeRegistry,
  jupyterHighlightStyle
} from '@jupyterlab/codemirror'

import {
  LanguageSupport,
  LRLanguage,
  syntaxHighlighting,
  // HighlightStyle,
  // defaultHighlightStyle
} from '@codemirror/language';

import { EditorView } from '@codemirror/view';

// import { tags as t } from '@lezer/highlight';

import { buildParser } from '@lezer/generator';

/**
 * Initialization data for the unicodelab-ts extension.
 */
export const algorithm_plugin: JupyterFrontEndPlugin<void> = {
  id: 'unicodelab-ts:algorithm',
  autoStart: true,
  // provides: snippetToken, // For providing services
  requires: [IEditorLanguageRegistry, IEditorThemeRegistry],
  optional: [],
  activate: (
    app: JupyterFrontEnd,
    lang_registry: IEditorLanguageRegistry,
    theme_registry: IEditorThemeRegistry
  ) => {

    theme_registry.addTheme({
      name: 'algorithm',
      displayName: 'Algorithm',
      theme: [
        EditorView.baseTheme({}),
        syntaxHighlighting(jupyterHighlightStyle), // Not recognized

        // syntaxHighlighting(defaultHighlightStyle), // Not recognized

        /*
        syntaxHighlighting(HighlightStyle.define([
          {tag: t.propertyName, color: "#fc6"},
          {tag: t.number, color: "#f5d", fontStyle: "italic"},
          {tag: t.string, color: "#f0e", fontStyle: "bold"}
        ]))
        */
      ]
    });

    lang_registry.addLanguage({
      name: 'algorithm',
      displayName: 'Algorithm',
      mime: 'text/algorithm',
      extensions: ["algorithm"],
      support: new LanguageSupport(
        LRLanguage.define({
          parser: buildParser(`
@top File { (Identifier | Number | String)+ }

@skip { space }

@tokens {
  space { @whitespace+ }
  Identifier { $[A-Za-z_]+ }
  Number { $[0-9]+ }
  String { '"' !["]* '"' }
}

@external propSource algorithmHighlight from "./highlight.ts"
`)
        })
      )
    });
  }
};