@here.build/arrival-lsp

Scheme→TS type lens: lower Scheme to virtual TypeScript, type-check it with tsc's LanguageService (never execute), and lift diagnostics, hover, completions, and definitions onto .scm spans.

This is not the Language Server Protocol. The same surface ships as Node, browser, and worker entries.

Install

pnpm add @here.build/arrival-lsp

Depends on TypeScript 6.

Usage (Node)

import { createSchemeLanguageService } from "@here.build/arrival-lsp";

const ls = createSchemeLanguageService();
const diags = ls.getSemanticDiagnostics(`(define z (car 5))`);

(car 5) is a tsc error on the 5 in the Scheme source — start / length / line / character are Scheme coordinates, not the emitted TS. Hover, completions, and go-to-definition use the same lift:

• getQuickInfoAtPosition(scheme, offset)
• getCompletionsAtPosition(scheme, offset) / getCompletionContext(scheme, offset)
• getDefinitionAtPosition(scheme, offset)

Virtual TS is type-checked, never executed.

Subpaths

| Export | Runtime | | ------------- | ------------------------------------------------------------------------------------------------------------------------------- | | . | Node — disk prelude + the installed typescript package libs. | | ./browser | Browser — bundled prelude + inlined TS libs; no fs. createBrowserSchemeLanguageService. | | ./worker | (Shared)Worker entry. Importing it inside the worker attaches the server to the worker's ports. | | ./ls-client | Light main-thread client (connectSchemeLs). Talks to a worker-hosted service without pulling typescript into the UI bundle. |

Do not import ./ls-protocol from the UI thread — that barrel includes the heavy serve side. Use ./ls-client on the main thread and ./worker inside the worker.

Advanced (host wiring, incomplete prefixes, Scheme↔TS spans, (require …)):

| Export | For | | ---------------- | ----------------------------------------------------- | | ./host-prelude | Assemble a host option from a host type registry. | | ./balance | Close an incomplete Scheme prefix for cursor queries. | | ./span-map | Bidirectional position map over the lowered TS. | | ./require-path | Resolve (require …) against a project file table. |

Related

• @here.build/arrival-internals-types-prelude — builtin .d.ts the lens declaration-merges so Scheme programs type-check under tsc.
• @here.build/arrival-types-bridge — lowering (Scheme → virtual TS). See also docs/layer-t-design.md (Σ∩T masking; law at arrival/docs/static-plane.md).
• @here.build/arrival-codemirror — CodeMirror 6 editor that consumes this service.

Develop

From this package:

pnpm typecheck   # tsc -p tsconfig.test.json --noEmit
pnpm test

License

MIT.