Aster Lang TypeScript Compiler

TypeScript implementation of the Aster CNL (Controlled Natural Language) compiler pipeline.

Overview

Aster is a pragmatic, type-safe language with human-readable controlled natural language syntax. This package provides the pure TypeScript compiler infrastructure:

• Canonicalizer: Normalizes CNL source code
• Lexer: Tokenizes source with multi-language lexicon support
• Parser: Generates AST from token stream
• Core IR: Intermediate representation
• Type Checker: Static type analysis
• LSP Server: Language Server Protocol implementation

Installation

pnpm install @aster-cloud/aster-lang-ts

Quick Start

import { parseSource, resolveAndLowerChecked } from '@aster-cloud/aster-lang-ts';

// Compile pipeline: canonicalize → lex → parse → name resolution (R1) → lower → name resolution (R2)
const source = `
Module greeting.

Rule greet given name, produce:
  Return Text.concat("Hello, ", name).
`;

const { ast } = parseSource(source);
// Throws NameResolutionError (E8xx diagnostics) instead of returning Core with unresolved names
const { core, diagnostics } = resolveAndLowerChecked(ast);

Raw lowering (lowerModule) and the unchecked resolveAndLower are internal and not exported: every public path to Core IR runs name resolution and refuses to emit IR on resolution errors. Use compile / compileAndTypecheck from @aster-cloud/aster-lang-ts/browser, resolveAndLowerChecked, or resolvePolicyTypes.

Multi-Language Support

Aster supports writing policies in multiple natural languages:

import { canonicalize, lex, parse } from '@aster-cloud/aster-lang-ts';
import { ZH_CN } from '@aster-cloud/aster-lang-ts/lexicons/zh-CN';

const zhSource = `
模块 问候。

规则 问候 给定 姓名，产出：
  返回「你好，」 加 姓名。
`;

const tokens = lex(canonicalize(zhSource, ZH_CN), ZH_CN);
const ast = parse(tokens);

Supported languages:

• English (en-US) - Default
• Simplified Chinese (zh-CN)
• German (de-DE)

Current CNL Style

• Type inference is the default; examples avoid explicit type annotations.
• Operator-call chaining is removed. Use standard calls or infix operators.
• Statements end with periods, and block headers end with colons.

Documentation

• docs/overview.md
• docs/cnl-syntax.md
• docs/type-inference.md
• docs/operator-call.md
• docs/examples.md
• docs/contributing.md
• Localized docs:
• English (default): same list above.
• 简体中文: docs/zh/overview.md, docs/zh/cnl-syntax.md, docs/zh/type-inference.md, docs/zh/operator-call.md, docs/zh/examples.md, docs/zh/contributing.md
• Deutsch: docs/de/overview.md, docs/de/cnl-syntax.md, docs/de/type-inference.md, docs/de/operator-call.md, docs/de/examples.md, docs/de/contributing.md

Development

# Install dependencies
pnpm install

# Build
pnpm build

# Run tests
pnpm test:unit

# Start LSP server
pnpm lsp

# REPL
pnpm repl

Project Structure

src/
  ├── canonicalizer.ts    # Source normalization
  ├── lexer.ts            # Tokenization
  ├── parser.ts           # AST generation
  ├── ast.ts              # AST definitions
  ├── lower_to_core.ts    # Core IR lowering
  ├── core_ir.ts          # Core IR definitions
  ├── typecheck/          # Type checker
  ├── lsp/                # Language Server Protocol
  └── config/
      └── lexicons/       # Multi-language lexicons
          ├── en-US.ts
          ├── zh-CN.ts
          └── de-DE.ts

API Reference

Core Exports

Lexicon Exports

import { EN_US } from '@aster-cloud/aster-lang-ts/lexicons/en-US';
import { ZH_CN } from '@aster-cloud/aster-lang-ts/lexicons/zh-CN';
import { DE_DE } from '@aster-cloud/aster-lang-ts/lexicons/de-DE';

License

MIT