Nodeon is a programming language that compiles to JavaScript. It combines Python's simplicity with TypeScript's robustness while maintaining full compatibility with the JS/Node.js ecosystem.

fn greet(name) {
  print("Hello {name}!")
}

greet("World")

Why Nodeon

• No noise — no semicolons, no mandatory parentheses in if/for/while, implicit returns
• Natural interpolation — "Hello {name}" with double quotes, 'raw strings' without interpolation
• Optional typing — write types when you need them, erased at compile time
• Strict equality by default — == compiles to ===, != to !==
• Full JS ecosystem — imports, classes, async/await, everything compiles to standard JS
• DX first — CLI with colored errors, VS Code extension, full Language Server
• Self-hosting — the compiler is written in Nodeon and compiles itself

Installation

Requirements: Node.js 18+, npm.

npm install           # install dependencies
npm test              # run 307 tests

CLI

# Compile .no → .js
node cli/bin.js build hello.no

# Compile with minification
node cli/bin.js build -min hello.no

# Compile with source map
node cli/bin.js build --map hello.no

# Compile and run in memory
node cli/bin.js run hello.no

# Version
node cli/bin.js --version

Compilation errors show line, column, and caret:

error: Unexpected character '@' at 3:5
  --> example.no:3:5
   3 | x = @invalid
     |     ^

Quick Syntax Reference

| Nodeon | JavaScript | |--------|-----------| | x = 42 | let x = 42; | | const PI = 3.14 | const PI = 3.14; | | fn add(a, b) { a + b } | function add(a, b) { return a + b; } | | print("Hello {name}") | console.log(`Hello ${name}`) | | if x > 0 { ... } | if (x > 0) { ... } | | for i in 0..10 { ... } | for (let i = 0; i <= 10; i++) { ... } | | for item in items { ... } | for (const item of items) { ... } | | x == 5 | x === 5 | | obj?.prop ?? fallback | obj?.prop ?? fallback | | match x { case 1 { ... } } | if (x === 1) { ... } | | const { a, b } = obj | const { a, b } = obj; | | fn add(a: number, b: number) { ... } | function add(a, b) { ... } |

Strings

• Double-quoted "Hello {name}" — interpolation with {expr}
• Single-quoted 'raw {no interpolation}' — literal, no interpolation
• Backtick `Hello ${name}` — JS-standard interpolation

Functions

fn double(x) { x * 2 }                    // implicit return
fn clamp(v, min = 0, max = 100) { ... }   // default parameters
fn sum(...nums) { ... }                    // rest parameters
async fn fetch(url) { ... }               // async functions
add = (a, b) => a + b                     // arrow functions
fn* generate() { yield 1 }               // generators

Classes

class Dog extends Animal {
  #name                              // private field
  static count = 0                   // static field

  constructor(name) {
    super()
    this.#name = name
  }

  fn bark() {
    print("{this.#name} says Woof!")
  }
}

Control Flow

// if / else if / else
if score >= 90 { print("A") }
else if score >= 80 { print("B") }
else { print("F") }

// switch (block-style, no fall-through)
switch color {
  case "red" { print("Stop") }
  case "green" { print("Go") }
  default { print("Unknown") }
}

// pattern matching with guard clauses
match shape {
  case "circle" { return PI * r * r }
  case "square" when side > 0 { return side * side }
  default { return 0 }
}

// loops
for i in 0..10 { print(i) }
for item in items { print(item) }
while x > 0 { x = x - 1 }
do { x = x - 1 } while x > 0

Destructuring & Types

const { name, age } = person         // object destructuring
const [first, ...rest] = items       // array destructuring

fn add(a: number, b: number): number {   // type annotations
  return a + b                           // (erased at compile time)
}

Enums & Interfaces

enum Color { Red, Green, Blue }      // → Object.freeze({Red: 0, ...})

interface Shape {                    // type-only (stripped from output)
  area(): number
}

Comments

// Line comment
/* Block comment */

Note: # is NOT for comments — it's for private class fields (#name).

Project Structure

src-ts-deprecated/            # TypeScript compiler (Deprecated)
  compiler/
    lexer/                    # Tokenizer with line:col tracking
    parser/                   # Pratt parser (1700 lines)
    ast/                      # 70+ AST node type definitions
    generator/                # JS code generator + source map builder
    type-checker.ts           # Structural type checker with inference
    compile.ts                # Public API: compile(), compileToAST()
  language/                   # Keywords, operators, tokens, precedence
src/                          # Self-hosted compiler (15 .no modules)
  compiler/                   # Componentized: lexer, parser (5 files), generator, type-checker
  language/                   # Language definitions in Nodeon
dist/                         # Compiled self-hosted compiler
  nodeon-compiler.cjs         # Bundled compiler (98.5kb)
cli/                          # CLI (build/run/version)
packages/
  language-server/            # Full LSP server (1400+ lines)
  vscode-extension/           # VS Code extension (syntax + LSP client)
scripts/                      # Build scripts for bootstrap pipeline
tests/                        # 307 Vitest tests (lexer, parser, e2e, bootstrap)
examples/                     # Example .no programs
docs/                         # Technical documentation

Testing

npm test              # run all 307 tests
npm run test:watch    # watch mode

307 tests covering:

• Lexer — tokens, numbers (hex/bin/oct/sci/bigint), strings, template literals, operators, comments, position tracking
• Parser — declarations, functions, control flow, switch, try/catch, expressions, interpolation, classes, imports, destructuring, pattern matching, type annotations
• E2E — full compilation .no → .js verifying correct output
• Bootstrap — self-compilation: compiled compiler compiles all 15 of its own .no source files

VS Code Extension

The extension provides professional IDE support:

• Syntax highlighting — functions, methods, classes, parameters, properties, constants, types, interpolation, regex
• Semantic tokens — AST-based highlighting that differentiates function calls, method calls, class references, parameters, and properties
• Diagnostics — real-time parse errors + type warnings + semantic analysis (undefined variables, unused declarations)
• Hover — keyword documentation + symbol info
• Completions — keywords + built-ins + document symbols
• Go-to-Definition — jump to fn/class/variable declarations
• Find References — locate all usages of a symbol
• Rename Symbol — rename across document
• Formatting — auto-indent with brace tracking
• Code Actions — quick fixes (declare with let, type suggestions)

Install Extension

cd packages/vscode-extension
npm install
npm run build
# F5 in VS Code to launch Extension Development Host

Package VSIX

cd packages/vscode-extension
npx vsce package
code --install-extension nodeon-vscode-extension-0.0.1.vsix

Self-Hosting

The Nodeon compiler is self-hosting — it can compile its own source code:

node scripts/build-no.js     # Compile 15 .no files → dist-no/*.js
node scripts/bundle-no.js    # Bundle → dist-no/nodeon-compiler.cjs

The self-hosted compiler is a full reimplementation in Nodeon (15 modules, ~3000 lines) with a componentized parser architecture:

ParserBase → ParserTypes → ParserExpressions → ParserStatements → Parser

Documentation

See docs/ARCHITECTURE.md for exhaustive technical documentation covering:

• Complete language specification
• Compiler pipeline (lexer → parser → type checker → generator)
• AST node reference (70+ node types)
• LSP implementation details
• Self-hosting bootstrap process
• Design decisions and rationale

Roadmap

Completed ✅

• [x] Lexer with line:col tracking
• [x] Pratt parser with ES2020+ support
• [x] JS generator with minification
• [x] CLI build/run with colored errors
• [x] Destructuring (object/array)
• [x] Type annotations (TypeScript-style erasure)
• [x] Pattern matching with guard clauses
• [x] Source maps (V3 spec with VLQ encoding)
• [x] Full LSP (diagnostics, hover, completions, go-to-definition, formatting, rename, references, semantic tokens, code actions)
• [x] VS Code extension with professional syntax highlighting
• [x] Self-hosting bootstrap (compiler compiles itself)
• [x] 307 tests with Vitest
• [x] GitHub Actions CI (Node 18/20/22)

Next 🚧

• [ ] npm publish — npm install -g nodeon
• [ ] Multi-file compilation — resolve imports across .no files
• [ ] Exhaustive type checking — narrowing, exhaustiveness checks
• [ ] VS Code Marketplace — publish extension

Future 🔭

• [ ] Nodeon stdlib — idiomatic wrappers for fs, path, http
• [ ] WASM target — compile to WebAssembly
• [ ] Integrated bundler — resolve imports and emit a single .js

License

MIT