The Prose language

ProseLanguage gives a .loom's prose its editor support. Prose is Markdown, so this service extends volar-service-markdown — headings, links, lists, fenced-code highlighting, and formatting — and registers it as a language of Loom's own. A {Prose} section, and the prose of every other section, projects to a prose document the editor reads through this service.

Prose carries Loom's anchors too, the ::[…] links between sections. Their navigation already rides the root mirror, where LoomLanguage answers go-to-definition and references over the whole file. So ProseLanguage adds the Markdown layer beneath them, and the two compose in the editor: Markdown for the prose, Loom for the anchors.

The prose document's languageId is prose, distinct from a real .md file, so a .loom's prose routes here and nothing else claims it. create from volar-service-markdown takes a document selector, and pointing it at prose retargets the Markdown service onto Loom's prose without forking it.

The service

ProseLanguage loads volar-service-markdown on demand and wraps it under the prose selector. The Markdown service is a heavy dependency the editor needs only once a .loom opens its prose, so the import is dynamic — deferred to the first call rather than paid at startup. A load that fails leaves the service with no plugins, degrading prose to plain text while every other language serves on. It needs no host capability: the Markdown service reads the document on its own, and Loom's own answers come from the root.

TypeScript

export const ProseLanguage = defineLanguageService({
  id: 'prose',
  displayName: 'Prose',
  extensions: [],
  plugins: () =>
    Effect.tryPromise(() => import('volar-service-markdown')).pipe(
      Effect.map((markdown) => [markdown.create({ documentSelector: ['prose'] })]),
      Effect.orElseSucceed(() => []),
    ),
})

What this module draws on

Effect runs the on-demand load and builds the plugins result; volar-service-markdown is imported dynamically inside it rather than at the module head. The LanguageService module gives defineLanguageService, the contract this service satisfies.

TypeScript

import { Effect } from 'effect'
import { defineLanguageService } from './LanguageService'

The module

TypeScript

::[What this module draws on]

::[The service]

Loom