The language registry

The Loom language server resolves which languages a project has activated — built-in modules and loaded loom-service-<id> packages — into one active set. The LanguageRegistry indexes that set so the server finds a language by a single lookup, not a scan: by id for a section's declared language, by extension for a tangle path.

Imports

The registry draws on Effect — HashMap for its two indexes, Option for a lookup that can miss — and on the LanguageService type it indexes.

TypeScript

import { Context, Effect, HashMap, Layer, Option } from 'effect'
import type { LanguageService } from './LanguageService'

The active set

ActiveLanguages holds the language set the server resolves from loom.config.json. It is empty until the server fills it — the registry over an empty set simply finds nothing.

TypeScript

export class ActiveLanguages extends Context.Service<ActiveLanguages>()('ActiveLanguages', {
  make: Effect.succeed({ all: [] as ReadonlyArray<LanguageService> }),
}) {
  static readonly layer = Layer.effect(this, this.make)
}

The registry

The registry builds two maps over the active set — one keyed by id, one by each service's extensions — and returns an Option for each lookup: present when a language claims that id or extension, absent otherwise. The all field keeps the full set for the collect-and-register pass that hands every service's plugins to Volar.

TypeScript

export class LanguageRegistry extends Context.Service<LanguageRegistry>()('LanguageRegistry', {
  make: Effect.gen(function* () {
    const { all } = yield* ActiveLanguages
    const byId = HashMap.fromIterable(all.map((s) => [s.id, s] as const))
    const byExtension = HashMap.fromIterable(
      all.flatMap((s) => s.extensions.map((e) => [e, s] as const)),
    )
    return {
      byId: (id: string): Option.Option<LanguageService> => HashMap.get(byId, id),
      byExtension: (ext: string): Option.Option<LanguageService> => HashMap.get(byExtension, ext),
      all,
    }
  }),
}) {
  static readonly layer = Layer.effect(this, this.make)
}

The module

TypeScript

::[Imports]

::[The active set]

::[The registry]

Loom