This package exposes the Decodal evaluator and shared language service to browsers and other JavaScript runtimes that can load WebAssembly modules. It is generated from the Rust crate in crates/decodal-wasm with wasm-pack and is used by the official playground.

Use decodal-codemirror separately when you need CodeMirror 6 language support.

Install

npm install decodal-wasm

JSR:

deno add jsr:@hare/decodal-wasm

Usage

import init, { DecodalLanguageService } from 'decodal-wasm';

await init();

const files = {
  'main.dcdl': 'let schema = import "./schema.dcdl"; in schema.Server',
  'schema.dcdl': 'Server = App.Server & { port = 8080; };',
};

const service = new DecodalLanguageService({
  globals: {
    App: {
      Server: {
        port: { $decodal: 'Int' },
      },
    },
  },
  loadImport(_currentKey, specifier) {
    const key = specifier.startsWith('./') ? specifier.slice(2) : specifier;
    return { kind: 'source', key, name: key, source: files[key] };
  },
  completeImport() {
    return ['./schema.dcdl'];
  },
});

const result = service.evaluate('main.dcdl', 'main.dcdl', files['main.dcdl']);

console.log(JSON.parse(result));

const completion = service.complete(
  'main.dcdl',
  'App.Server.po',
  'App.Server.po'.length,
  false,
);

console.log(JSON.parse(completion));

globals, loadImport, and completeImport are host-owned. The package does not assume a filesystem or virtual project model. Import callbacks are synchronous; preload or cache remote content before evaluation.

Plain strings, numbers, booleans, arrays, and objects are concrete host values. Use { $decodal: 'String' | 'Int' | 'Float' | 'Bool' } for primitive schemas and { $decodal: 'Array', item: value } for array schemas. Descriptors also accept constraints and default.

Methods return JSON strings so callers can handle diagnostics and successful results without depending on Rust data structures.